Assessment of Proliferation Index and Pathological Features as Prognostic Potential of Breast Cancer in Ethiopia

Abstract

Background: Analysis of proliferation status in breast cancer can be associated with tumor aggressiveness. Uncontrolled proliferation has been accepted as a distinct hallmark of cancer and act as an important determinant of cancer outcome. Recently measuring proliferation used as predictive potential and crucial element of treatment decision in patients with breast cancer. Aim: We therefore aimed to assess the frequency proliferation rate by using mitotic count and Ki-67 index to associate with other prognostic markers. Methods: A prospective study of 197 newly diagnosed breast cancer tissues from women received surgery as initial management in three different hospital in Addis Ababa, Ethiopia from January 2013 to December 2015 were included in the study. Histology slides were evaluated for the histological type, grade (by modified Nottingham grade score). Mitotic count quantified as number of mitoses per 10 high power fields (HPF) at the tumor periphery. Less than and seven mitoses per 10 fields scored 1 point, 8-16 scored 2 points, and more than 17 scored 3 points. Immunohistochemical staining of Ki- 67 was performed and the proliferation rate was expressed as percentage of stained tumor cell nuclei. Associations of the Ki67 index with other prognostic factors were evaluated both as continuous and categorical variables. Results: The Mean ± SD mitotic activity index was 15.7 ± 10.6 while the median was 14/10 HPF. Mitotic count was found 0-7 mitoses per 10 HPF in 42/197 (21.3%) cases, between 8 and 14 mitoses per 10 HPF in 74/197 (37.6%) cases and >15 in 81/197 (41.1%) cases. Ductal type BC was associated with high mitotic count than lobular and other histological BC types which is statistically significant (p=0.009). High mitotic count was significantly associated with aggressive features of the primary tumors (negative hormonal receptor (ER- and PR-) p 60 yrs of old. The mean value of G2 and G3 tumor were higher than G1 tumor and it is statistically significant (p <0.001). The Ki-67 mean value was found lower in Hormone receptor posetive (ER +, PR +) than hormone receptor negative (ER-, PR-). The deference was statistically significant (p=0.001) and (p=0.005). While Her-2 posetive tumor found higher mean Ki-67 value than Her-2 negative tumor and also the difference was statistically significant (p=0.001). Conclusion: Clinical utility of Mitotic count and Ki-67 in combination with other prognostic markers can better predict breast cancer outcome. Therefore we suggest that Ki-67 index should be added to treatment plan when considering adjuvant chemotherapy and prognostic stratification.