Relationship between tumor infiltrating lymphocytes and hormone-sensitive (breast and prostate) cancer survival: cases received at Yaoundé General Hospital (Cameroon) from 2019 to 2023.

Introduction: cancer ranks as the second leading cause of mortality worldwide, manifesting in diverse forms and impacting various tissues, notably prostate cancer (PCa) in men and breast cancer (BCa) in women. Cancer is a malignant tumor that can induce an immune response. During this reaction, immune cells are produced which are responsible for ridding the body of senescent and/or tumor cells, and constitute tumor effectors. Studies have shown that the presence of tumor-infiltrating lymphocytes (TILs) is a good prognostic marker for assessing survival in cancer patients; however, no similar data have yet been published in Cameroon. Methods: the aim of this study was to investigate the relationship between TILs and the survival of breast and prostate cancer patients at Yaoundé General Hospital (YGH) between 2019 and 2023. For this, a retrospective and cross-sectional study was undertaken at the Oncology Department and the Anatomo-Cytopathology Laboratory of YGH. A consecutive non-probability sampling (from August to October 2023) of 212 breast cancer patients and 89 prostate cancer patients who agreed to participate in the study constituted our sample. Variables were survival, TILs, sociodemographic, clinical, and pathological characteristics of patients. The TILs were estimated after Hematoxylin-Eosin (HE) staining and staged as low, middle and high TILs rate. The variables were sociodemographic characteristics (age, education level, religion, marital status, ethnolinguistic area, and menopause); clinical characteristics (affected breast, histological type, histological grade, type of treatment, AJCC stage, consistency of discovery); different grades of TILs. Furthermore, the correlation between TILs and chemotherapy as well as TILs and survival were analyzed. The obtained data were analyzed using Microsoft Excel, Epi-info 7 and SPSS software and statistical significance was considered at p< 0.05. Furthermore, the Cox regression analysis to identify factors associated with survival was performed. Results: the mean age was 43.56 ± 11.90 years for BCa with stage II and SBR grade II being the most common with proportions of 48.34% and 54.72%, respectively (n= 212). While in PCa, the mean age was 75 to 84 years (34.83%, n= 89) with stage II being the most frequent. Microscopic analysis of breast tissues revealed four TILs grades: absent (17.45%), low (18.40%), intermediate (27.83%) and high TIL grade (36.32%), while in PCa the most represented TILs grade was intermediate (31.46%). In BCa the intermediate TILs grade was positively associated with a good response to chemotherapy (p< 0.05). The overall 5-year survival in this study was around 44% for BCa, whereas it was 42 months for those with infiltration in PCa. No positive correlation was found between TILs grade and survival in BCa patients (p= 0.45), while in PCa, it was found that TILs are significantly correlated (p =0.016) with survival. Patients with prostate cancer who had not taken treatment had a 7.23 greater risk of death (HR: 7.23, 95% CI 1.21-53.14; p= 0.049) than those who had. Conclusion: no positive association was observed between TILs as graded and 5-year survival in BCa patients; however, it may have prognostic value in PCa patients. Further studies are encouraged to investigate the association between BCa molecular groups and TILs.