RESEARCH Open Access Survival and associated factors among patients with oral squamous cell carcinoma (OSCC) in Mulago hospital, Kampala, Uganda Juliet Asio1*, Adriane Kamulegeya2 and Cecily Banura3 Abstract Background: Despite improvements in diagnosis and patient management, survival and prognostic factors of patients with oral squamous cell carcinoma (OSCC) remains largely unknown in most of Sub Saharan Africa. Objective: To establish survival and associated factors among patients with oral squamous cell carcinoma treated at Mulago Hospital Complex, Kampala. Methods: We conducted a retrospective cohort study among histologically confirmed oral squamous cell carcinoma (OSCC) patients seen at our centre from January 1st 2002 to December 31st 2011. Survival was analysed using Kaplan-Meier method and comparison between associated variables made using Log rank-test. Cox proportional hazards model was used to determine independent predictors of survival. P-values of less than 0.05 were considered statistically significant. Results: A total of 384 patients (229 males and 155 females) were included in this analysis. The overall mean age was 55.2 (SD 4.1) years. The 384 patients studied contributed a total of 399.17 person-years of follow-up. 111 deaths were observed, giving an overall death rate of 27.81 per 100 person-years [95% CI; 22.97–32.65]. The two-year and five-year survival rates were 43.6% (135/384) and 20.7% (50/384), respectively. Tumours arising from the lip had the best five-year survival rate (100%), while tumours arising from the floor of the mouth, alveolus and the gingiva had the worst prognosis with five-year survival rates of 0%, 0% and 15.9%, respectively. Independent predictors of survival were clinical stage (p = 0.001), poorly differentiated histo-pathological grade (p < 0.001), male gender (p = 0.001), age > 55 years at time of diagnosis (p = 0.02) and moderately differentiated histo-pathological grade (p = 0.027). However, tobacco & alcohol consumption, tumour location and treatment group were not associated with survival (p > 0.05). Conclusions: The five-year survival rate of OSCC was poor at 20.7%. Male gender, late clinical stage at presentation, poor histo-pathological types and advanced age were independent prognostic factors of survival. Early detection through screening and prompt treatment could improve survival. Keywords: Oral squamous cell carcinoma, Uganda, Survival, Clinical-pathological presentation * Correspondence: julietasio@yahoo.com 1HIV Reference Laboratory, Uganda Virus Research Institute, P. O. Box 49, Entebbe, Uganda Full list of author information is available at the end of the article Cancers of the Head & Neck © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Asio et al. Cancers of the Head & Neck (2018) 3:9 https://doi.org/10.1186/s41199-018-0036-6 http://crossmark.crossref.org/dialog/?doi=10.1186/s41199-018-0036-6&domain=pdf mailto:julietasio@yahoo.com http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/publicdomain/zero/1.0/ Background Oral squamous cell carcinoma (OSCC) is a potentially dis- figuring and debilitating disease that affects the physical appearance of patients and devastates their self-esteem. Globally, over 175,000 cases are diagnosed annually [1]. The age-adjusted incidence and mortality rates of OSCC increases with age and are greater in males than females [2]. It is well established that tobacco use and alcohol consumption are significant risk factors [3]. Some studies suggest that among people living with HIV, the risk of oral cancer is elevated [4]. The risk factors for Human Papilloma Virus (HPV) positive OSCC are mainly related to sexual habits rather than to tobacco and alcohol use in HPV negative OSCC [5]. Furthermore, over the past decade, oncogenic HPV type 16 has been linked to the development of some oral pharyngeal cancers but the association with oral cancer proper was not evident [6]. The detection of HPV DNA in some oral pharyngeal cancers has been linked to a favourable prognosis particularly among males [7]. Sub Saharan Africa (SSA) having a high burden of infection related cancers may provide unique circumstances in oral cancers worth researching. Despite improvements in diagnostic facilities and patient management, survival and prognostic factors of OSCC remain unknown in most of SSA. Data from the Kampala Cancer Registry showed that oral cancer (ICD-10 C00-C06) was a rare disease that contributed 1.1% cases in Uganda [8]. However, there is paucity of data on survival and prognostic factors of oral cancers in Uganda. Therefore, the purpose of this study was to establish survival rates and determine independent prognostic factors of survival among patients with OSCC. Methods Study design and setting Records of patients with histologically confirmed OSCC seen at Mulago Hospital Complex from January 1st 2002 to December 31st 2011 were reviewed. Mulago hospital is a national referral hospital, which has the only functional oral and maxillofacial surgery unit and the only radiotherapy unit serving the whole of Uganda and the neighbouring countries. Additionally, Mulago Hospital Complex shares location with the Uganda Can- cer Institute (UCI) that provides chemotherapy treatment and care of cancer patients in Uganda and neighbouring countries. Records of patients with OSCC were retrieved from the Oral and Maxillofacial department and their socio-demographic, clinical and pathological data was abstracted. At both UCI and the Radiotherapy depart- ment, registers were used to identify patients with OSCC. Records of patients with OSCC were then retrieved and their details recorded. Study population The sample size was determined using the following as- sumptions: the log rank comparisons of the probability of experiencing death in 5 years between patients with early disease and those with advanced disease at 0.47, power of 80%, 5% significance level, an effect size of 1.595 and adjusting for loss to follow-up of 10%. The total number of (events) deaths that were required was 149 and at least 270 participants were required for this study. Consecutive records of 384 index patients with a histological diagnosis of OSCC seen at Mulago Hospital Complex were retrieved for assessment. Records with missing important variables (e.g. date of diagnosis, site of lesion) or those with vague histological diagnosis (such as ‘moderately-well’ differentiated, ‘poorly-well’ differentiated), those of patients who presented with second primaries and patients who were referred to Hospice Uganda for terminal care, were excluded from the study. To eliminate duplicate recruits, patient demographic characteristics at different entry points of care were compared using hospital identification num- bers and patient details. From each eligible record, demographic characteristics, pre-operative tumour char- acteristics, TNM stage, tobacco and alcohol usage, treat- ment instituted, length of follow-up and survival status were abstracted. To determine the nodal status in TNM staging, both clinical and radiological findings were assessed whenever available, while the evaluation of me- tastases was based on chest x-ray reports. In some cases, follow-up phone calls were made to patients or their next of kin with recorded telephone contacts in order to ascer- tain the status of the patient. Statistics and analysis Statistical analyses were performed using STATA Version 12. The length of follow-up was defined as the period in months between the date of histological diagnosis and time to death or censoring. Cases were classified as alive, dead (if date of death was recorded) or lost to follow-up (date of last visit as recorded in patient’s file). Baseline characteristics for the patients were described using percentages for categorical variables and medians for continuous variables. Survival was calculated using the Kaplan-Meier analysis and the significance of the difference between survival curves for each variable was determined using the Breslow-test. P-values less than 0.05 were considered statistically significant. The Cox proportional hazards model was used to obtain independent predictors of sur- vival. Construction of the final model was done in stages. Initially, all variables with a p value < 0.25 at univariate analysis were included in the multivariable model. To test for goodness of fit of the multivariable model a plot of Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 2 of 10 Nelson–Aalen cumulative hazard estimate against Cox Snell residuals was plotted. Results Records of 512 patients were retrieved. One hundred twenty eight (25.0%) records were excluded due to missing data including: vague or no histological diagnosis, patients with second primaries, and patients referred to Hospice Uganda for terminal care. Therefore, 384 (75.0%) records were included in the analysis. In addition, 70 (13.7%) re- cords with no data on clinical stage at presentation were excluded from survival analysis. Socio-demographic characteristics, alcohol consumption and tobacco use The mean age of the 384 patients included in this study was 55.2 years with a standard deviation of 4.1 years. There were 229 (59.6%) males and 155 (40.4%) females. Males had a mean age of 55.8 years (SD = 19.9 years), whereas females had a mean age of 55.6 years (SD = 15.9 years). Most patients were in their sixth decade 104 (27.1%). Most patients came from the western re- gion of the country 130 (33.9%). Of the 214 patients with a history of education background, less than 40% had attained secondary level education (Table 1). Com- pared to females, more males reported use of tobacco and alcohol. Sub-site tumour presentation, histopathological grading and clinical stage The distribution of primary tumour sites, spread and clinical stage of OSCC is presented in Table 2. In descending order, the tongue (34.1%), palate (13.5%), buccal mucosa (13.3%) and floor of the mouth (12.2%) were the commonest primary sites. Majority 51.6% (n = 198) of patients had well differ- entiated tumours, and about one-fifth (21.9%, n = 84) had poorly differentiated tumours. Majority (61%) of the identified OSCC were in TNM stage III and IV (Table 1). Survival pattern of 384 patients with OSCC The 384 patients studied contributed a total of 399.17 person–years of follow-up. One hundred eleven deaths were observed, giving an overall death rate of 27.81 per 100 person–years [95% CI; 22.97–32.65]. The overall average survival time for patients with OSCC was 375 days. The two-year and five-year survival rates were respectively 43.6% (135/384) and 20.7% (50/384), (Table 3). The two-year and five-year survival rates were signifi- cant for age (p = 0.001), clinical stage (p < 0.001) and pathological stage (p < 0.001). There was no difference in gender, tumour localisation, treatment group and in patients with or without a history of either tobacco or al- cohol consumption (p > 0.05), (Table 4). Kaplan–Meier analysis and log-rank test were used for bivariate analysis. Kaplan–Meier curves were constructed for all patients and for significant variables (Figs. 1, 2, 3, 4 and 5). Predictors of survival among OSCC patients Construction of the final model containing variables found to be independently associated with survival of Table 1 Demographic, clinical and pathological characteristics of 384 OSCC patients Characteristic n(%) Gender Male 229(59.6) Female 155(40.4) Age (years) Mean (SD) 55.2(4.1) Tobacco use User 147(54.7) Non-User 122(45.4) Alcohol use User 140(52.6) Non-User 126(47.4) Geographical region Central 132(34.4) Eastern 72(18.7) Northern 41(10.7) Western 109(28.4) Non-Ugandan 30(7.8) Education level Tertiary 27(12.6) Secondary 44(20.6) Primary 68(31.8) None 75(35.0) Histo-pathological grade Well differentiated 198(51.5) Moderately differentiated 102(26.6) Poorly differentiated 84(21.9) Treatment modality Surgery 38(9.9) Radiotherapy 224(58.3) Chemotherapy 4(1.0) Surgery + Radiotherapy 41(10.7) Surgery + Chemotherapy 8(2.1) Surgery + Radiotherapy +Chemotherapy 8(2.1) Radiotherapy + Chemotherapy 3(0.8) None 58(15.1) Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 3 of 10 oral cancer was made using Cox proportional hazards model. A model which included all variables that had a P–value of less than 0.25 at univariate analysis was formed (Table 5). These included clinical stage, patho- logical variant, treatment group, gender, age and tobacco use. The variable tumour site (p = 0.26) was included on the basis of previous studies. The model was tested to verify whether the assump- tion of proportionality between early-stage and late stage disease patient categories. The proportionality of hazards assumption of the model was tested as a whole, and for each variable using the global test and the extended Cox model. The model was not significant based on the Schoenfeld’s test (p = 0.838) and the extended Cox model indicating that the data did not violate the pro- portional hazards assumption. There model was tested for interaction and confounding, using clinical stage as the main predictor of survival. The final model was thus determined as: h t; xð Þ¼h0 exp � 1:098clinical stage IIIIVð Þ þ0:027moderately differentiated tumour þ01:094poorly differentiated tumour þ0:023age� 0:731femaleÞ The model itself was significant (p < 0.001). It was also tested for goodness of fit using a plot of Nelson–Aalen cumulative hazard estimate against Cox Snell residuals which gave a good model. Assessment of selection bias on participants lost to follow-up A total of 141 (44.9%) participants were lost to follow-up during the study. This rate is higher than the acceptable 15%. The characteristics of these pa- tients were assessed to determine the possibility of se- lection bias. The patients who were lost to follow-up had similar characteristics to those who remained in the study except with reference to treatment group, as shown in Table 6 below. Table 2 Sub-site distribution, TNM classification and clinical stage at presentation of 384 patients with OSCC Variable Number Percentage Site Alveolus 18 4.7 Buccal Mucosa 51 13.3 Floor of mouth 47 12.2 Gingiva 43 11.2 Lip 16 4.2 Palate 52 13.5 Tongue 131 34.1 Otherα 26 6.8 T (Tumour) 1 41 10.7 2 142 37.0 3 91 23.7 4 62 16.1 X 48 12.5 N (Nodal involvement) 0 151 39.3 1 63 16.5 2 106 27.6 3 22 5.7 X 42 10.9 M (Metastasis) 0 228 59.4 1 86 22.4 X 70 18.2 Clinical Stage (Based on TNM staging system) I 23 6.0 II 57 14.8 III 148 38.5 IV 86 22.5 X 70 18.2 αOther includes Commissure, Buccal sulcus, Retromolar trigone, Sublingual salivary glands X Missing data Table 3 Survival Pattern of 384 patients with OSCC Time (years) Total number Deaths Censored Survival 95% Confidence Interval 0 384 50 199 0.824 0.775 0.864 1 135 40 45 0.531 0.450 0.606 2 50 8 11 0.436 0.347 0.521 3 31 10 6 0.280 0.189 0.378 4 15 0 2 0.280 0.189 0.378 5 13 3 3 0.207 0.117 0.314 Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 4 of 10 Discussion This study, to the best of our knowledge presents one of a few on survival of OSCC patients in Sub Saharan Africa. It showed poor survival of patients with OSCC (20.7%) after five years and almost half of them (43.6%) had died within 2 years of diagnosis. Our findings are similar to the low five-year survival rate observed in Egypt for intra oral cancers (20.8%) [9]. However, better survival especially for stages III and IV has been re- ported in resource rich countries like Taiwan 26.6% and 11.8% [10], Brazil 32.6% and 24.5% [11] and the USA [12]. This discrepancy may be a reflection of better screening programs for early detection of cases and better treatment modalities, which ultimately improves survival, in the better resourced countries. The case for standardised treatment and its effect on survival irre- spective of the difference in ethnicity and economic sta- tus has already been made for all head and neck squamous cell carcinomas [13]. Gender had a significant effect on survival in our study with the risk of death two times greater in males compared to females (Table 5 and Fig. 2). The effect of gender on survival remains mixed and unclear. Whereas some studies suggest a greater survival for fe- males [14, 15], Mehta et al. reported lesser improve- ment in survival for females with oral cavity and oral pharyngeal carcinomas [16]. Other studies have re- ported no significant difference in survival between males and females [10]. It is believed that more males than females are affected by OSCC and have worse sur- vival because of their increased exposure to tobacco and alcohol [2]. Furthermore, the males have poor health seeking behaviours, which may translate into de- layed diagnosis and treatment initiation [17]. Age was a significant prognostic factor for survival in this study (Table 5 and Fig. 3). Patients who presented with OSCC and were above 55 years had a significantly shorter survival time as compared to those who were younger (p = 0.001). Our findings are consistent with studies conducted in Brazil [11], USA [16], Taiwan [10] and Egypt [9]. There seems to be a general agreement that the lower survival among older patients may be re- lated to the higher rates of co-morbidities associated with ageing. It is also possible that these co-morbidities preclude the older patients from long surgical interven- tions which disadvantages their survival yet radiotherapy alone has been reported to lead to worse prognosis [11, 18]. In addition, with the emerging role of HPV, in oral and oral pharyngeal cancers, it may be that the younger population has a different causative factor hence better outcomes. However, a study from Mbarara in western Uganda showed a low prevalence of HPV among the head and neck cancers [19]. Education level, alcohol consumption and tobacco smoking were not significant predictors of survival. However, determination of cigarette smoking and to- bacco and alcohol use, post event, may not be accurate thus making determination of their influence on patient survival hard to establish [20]. Education level is a sur- rogate for socio-economic status which has been shown Table 4 Univariate Analysis of 384 Patients with OSCC Variable Survival rate (%) P value (log-rank)2-year 5-year Gender Male 43.3 22.9 0.053 Female 59.2 30.1 Age (years) ≤ 55 69.7 53.7 0.001 > 55 34.0 8.8 Tobacco Use User 47.7 15.8 0.091 Non-User 49.6 29.8 Alcohol Use User 46.6 26.3 0.460 Non-User 50.7 21.0 Tumour Location Alveolus 59.3 0.0 0.255 Buccal mucosa 47.0 19.6 Floor of mouth 34.5 0.0 Gingiva 39.7 15.9 Lip 100.0 100.0 Palate 52.3 43.6 Tongue 53.3 21.2 Other 53.9 53.9 Clinical Stage I 100.0 100.0 < 0.001 II 69.1 61.5 III 41.7 14.5 IV 35.4 0.0 Histo-pathological grade Well differentiated 64.9 42.2 < 0.001 Moderately differentiated 50.1 21.7 Poorly differentiated 26.4 0.0 Treatment Group Surgery 73.8 61.5 0.103 Radiotherapy 47.5 27.6 Chemotherapy 100.0 0.0 At least 2 55.3 12.3 Other – Commissure, Buccal sulcus, Retromolar trigone, Sublingual salivary glands At least 2 – Surgery and Radiotherapy or Surgery and Chemotherapy P value is for 5-year survival Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 5 of 10 to affect survival. Therefore, more research needs to be done to establish why it had no effect in our study. Tumour site was not an independent predictor of survival. This was consistent with other studies [21] but different from others [9, 11, 14]. The possibility of mis- classification of original OSCC site is high given the complex anatomy of the oral cavity coupled with delayed presentation seen among our patients [22]. In advanced stages, there could be an overlap of oral tumours that arise from adjacent structures leading to misclassifica- tion. In this study, about two-thirds of patients pre- sented with late stage disease making misclassification of the original site of OSCC highly likely. OSCC arising from the lip had the best five-year sur- vival rate (100%) consistent with results from other studies [9, 14]. This may be because lip cancer is no- ticed earlier by patients and so they tend to seek care earlier. On the other hand, the floor of the mouth, al- veolus and the gingiva had the worst five-year survival rates of 0%, 0% and 15.9%, respectively. Our results are different from those obtained from other studies which showed that the tongue had the lowest survival rate [11, 12]. The differences in survival by tumour site could arise from the ease of early diagnosis, accessibil- ity for excision of the tumour with sufficient surgical margin and the different lymph node involvement that 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 12 24 36 48 60 72 84 96 108 Months after diagnosis Fig. 1 Kaplan–Meier estimates for 384 patients with OSCC Fig. 2 Kaplan–Meier estimates by Gender for patients with OSCC Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 6 of 10 each site presents. However, given the previously re- ported late presentation among our patients [22], tongue carcinomas may progress into the floor of the mouth making it hard to know the original site. In addition, some anatomic sites manifest greater meta- static capacity due to high lymphatic drainage [17]. We found an inverse relationship between tumour stage and survival (p < 0.001), which was consistent with other studies [9, 11, 18, 21, 23]. The five-year sur- vival rates were 100%, 61.5%, 14.5% and 0% for pa- tients with stages I, II, III and IV, respectively. A study conducted in Egypt found similar survival rates of 100%, 65.5%, 42.2% and 0% for stages I, II, III and IV disease, respectively [9]. However, the rates in our study are much lower than those reported by two studies that investigated the outcomes of OSCC after surgical and/or radiation therapy in America [24] and Taiwan [21]. The much lower survival rates reported in this study could be a reflection of the study popula- tion that comprised more of patients in clinical stages III and IV than those in stages I and II at presentation, which was much higher than those reported by other studies. Histo-pathological grading was a significant predictor of survival in this study. It is widely reported that prognosis is better with early stage well differentiated disease than other histo-pathological types [21]. In fact, the risk of death increased with less well differentiated tumours in this study. Patients with poorly and moder- ately differentiated tumours had three fold and almost two fold risk of death, respectively, compared to those who had well differentiated tumours. However, it is worth noting that some reports have not shown tumour grade to have an effect on survival [11, 23]. Fig. 3 Kaplan–Meier survival estimates by Age for patients with OSCC Fig. 4 Kaplan–Meier survival estimates by Clinical Stage for patients with OSCC Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 7 of 10 The type of treatment received by the patient was not a predictor of survival in this study. Of the 384 patients, about two-thirds (67.3%) received at least one form of treatment (Table 3). Radiotherapy, either alone or in combination with surgery was the most common treat- ment modality. Patients treated with surgery showed the highest two-year and five-year survival rates followed by surgery and radiotherapy. However, most untreated pa- tients died within 5 years and so did many of the pa- tients treated with radiotherapy alone or chemotherapy alone. However, several studies where surgery was the primary mode of treatment found treatment modality as a significant predictor of survival [10–12, 21]. The treat- ment modality is dependent on stage of disease and other parameters such as anatomical site, tumour size, distant metastasis, histological type and lymph node in- volvement [12]. While surgery alone may be recom- mended for patients with early stage disease, adjuvant radiotherapy or chemotherapy is indicated for patients with advanced stages [12]. The large number of patients lost to follow up could also explain why treatment modality was not a signifi- cant predictor of survival since patients who were lost to follow-up had a borderline difference (p = 0.057) from those who were not, with respect to treatment group. Patients who were lost to follow-up were most likely those who were assigned to treatment modalities that re- quired repeated visits such as chemotherapy and radio- therapy for advanced stage disease. It is also possible that many of the patients lost to follow-up were travel- ling long distances to access these treatment modalities, which would make re-visits expensive. Furthermore, pa- tients were classified solely on their treatment status without taking into consideration the dosage, duration and compliance with treatment received. In our setting sometimes surgery is not an option due limited surgical space. Sometimes this may lead to significant delays in accessing the service thus disease progression and change in stage [25]. This does have a significant effect on out- comes. It is not any different when it comes to radiother- apy were machine breakdowns and patient load likewise lead to delayed treatment compromising outcomes [26]. Limitations Our study was a hospital and not population-based study. It may therefore not be a representative sample of all the OSCC in Uganda. Data on HIV status of the patients and detection of HPV DNA in the tumours was not available. Fig. 5 Kaplan–Meier survival estimates by Histo-pathological Grade for patients with OSCC Table 5 Model showing the combined effect of significant variables Variables Hazard Ratio 95% Confidence Interval P value Clinical stage I & II 1 III & IV 2.998 1.584 5.674 0.001 Histo-pathological grade Well differentiated 1 Moderately differentiated 1.756 1.065 2.897 0.027 Poorly differentiated 2.985 1.798 4.957 < 0.001 Age ≤ 55 1 > 55 1.022 1.008 1.036 0.002 Gender Male 1 Female 0.482 0.310 0.749 0.001 Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 8 of 10 Seventy (13.7%) records with no data on clinical stage at presentation were excluded from survival analysis. How- ever, this did not affect the power of the study given that we sampled 384 records, compared to 270 required for this study. Conclusion Poor survival rates of oral cancer were recorded in this study, with two-year and five-year survival rates at 43.6% and 20.7% respectively. Male gender, late clinical stage at presentation due to delay in seeking medical care, poor histo-pathological types and advanced age were inde- pendent predictors of survival. Early detection through screening and prompt treatment could improve survival. Abbreviations CI: Confidence Interval; CMV: Cytomegalovirus; EBV: Epstein barr virus; HIV: Human immunodeficiency virus; HPV: Human Papilloma Virus; HR: Hazard Ratio; HSSP: Health sector strategic plan; IQR: Inter-quartile range; LTC: Lymphoma treatment centre; MoH: Ministry of Health; NCD: Non- communicable disease; OSCC: Oral Squamous Cell Carcinoma; SD: Standard deviation; SSA: Sub-Saharan Africa; STC: Solid tumour treatment centre; Table 6 Comparison of characteristics of patients enrolled and those lost to follow-up Variable Alive/Dead Lost to follow-up P value Total (n = 173) % Total (n = 141) % Gender Male 105 60.7 81 57.4 0.560 Female 68 39.3 60 42.6 Age (years) Median (IQR) 56 (44.5–66) 60 (47.5–66) 0.284 Tobacco use User 79 51.6 68 58.6 0.254 Non-user 74 48.4 48 41.4 Alcohol use User 85 55.9 55 48.2 0.215 Non-user 67 44.1 59 51.8 Tumour location Alveolus 6 3.6 10 7.1 0.764 Buccal mucosa 17 9.8 18 12.8 Floor of mouth 22 12.7 13 9.2 Gingiva 23 13.3 15 10.6 Lip 7 4.0 9 6.4 Palate 24 13.9 21 14.9 Tongue 62 35.8 47 33.3 Other 12 6.9 8 5.7 Clinical stage I 16 9.2 7 5.0 0.410 II 31 17.9 26 18.4 III 79 45.7 69 48.9 IV 47 27.2 39 27.7 Histo-pathological grade Well differentiated 80 45.8 89 63.1 9.351 Moderately differentiated 46 26.8 32 22.7 Poorly differentiated 47 27.4 20 14.2 Treatment group Surgery 18 11.8 17 15.0 0.057 Radiotherapy 110 71.9 72 63.7 Chemotherapy 2 1.3 1 0.9 At least 2 23 15 23 20.4 Asio et al. Cancers of the Head & Neck (2018) 3:9 Page 9 of 10 TNM: Tumour node metastasis; UCI: Uganda Cancer Institute; WHO: World Health Organisation Acknowledgements The authors are very grateful to Professor Charles Karamagi (PhD) and Ass Prof Joan Kalyango (PhD) of the Clinical Epidemiology Unit, College of Health Sciences, Makerere University Kampala Uganda, for mentoring JA and for their invaluable input during the study. Funding This study was personally funded. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Authors’ contributions JA contributed to the conception and design of the study, collected data, analysed and interpreted the data, drafted and revised the manuscript. CB participated in the design of the study, interpreted the data, and revised the manuscript. AK interpreted the data, and revised the manuscript. All authors have given their final approval of the version to be published. Ethics approval and consent to participate Ethical approval was sought and obtained from the School of Medicine Research and Ethics Committee, Makerere University, Kampala, Uganda. (Protocol number 3/SOMEREC/14/12). Consent waiver was sought for abstracting information from patients’ records. Consent for publication Not Applicable Competing interests The authors declare that they have no competing interests. Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Author details 1HIV Reference Laboratory, Uganda Virus Research Institute, P. O. Box 49, Entebbe, Uganda. 2Department of Dentistry, College of Health Sciences, Makerere University, P. O. Box 6717, Kampala, Uganda. 3Child Health and Development Centre, College of Health Sciences, Makerere University, P. O. Box 6717, Kampala, Uganda. 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Cancers of the Head & Neck (2018) 3:9 Page 10 of 10 Abstract Background Objective Methods Results Conclusions Background Methods Study design and setting Study population Statistics and analysis Results Socio-demographic characteristics, alcohol consumption and tobacco use Sub-site tumour presentation, histopathological grading and clinical stage Survival pattern of 384 patients with OSCC Predictors of survival among OSCC patients Assessment of selection bias on participants lost to follow-up Discussion Limitations Conclusion Abbreviations Acknowledgements Funding Availability of data and materials Authors’ contributions Ethics approval and consent to participate Consent for publication Competing interests Publisher’s Note Author details References