TNBC vs. Non-TNBC: A Five-Year Retrospective Review of Differences in Mean Age, Family History, Smoking History and Stage at Diagnosis at an Inner City University Program

Abstract

Background: In recent years, breast cancer has been classified on the basis of estrogen or progesterone receptor (ER/PR) status and whether the human epidermal growth factor 2 receptor (HER2/neu) protein is overexpressed. Based on this system, breast cancer is broadly divided into the triple negative breast cancer (TNBC) and the non-TNBC subtypes. TNBC is a subtype of breast cancer, notable for its propensity to metastasize early and display a comparatively more aggressive course than its non-TNBC counterpart. Certain clinico-pathologic and demographic risk factors have been associated with breast cancer. In this study, we aim to compare mean age, ethnicity, family history, tobacco use and stage at presentation between TNBC and non-TNBC subtypes at our inner city university program.

Methods: We reviewed data in our tumor registry between January 2000 and December 2005 with particular attention to mean age, race, family history, tobacco use and stage at presentation. We found a total of 445 patients with various subtypes of breast cancers. We included only those patients in whom the status of both ER/PR and the status of Her2/neu protein overexpression were recorded. Our strict selection criteria lead to an exclusion of about 103 patients. Out of the remaining 342 patients, 39 were TNBC and 303 were non-TNBC.

Results: Mean age of onset for TNBC vs. non-TNBC patients was 59.87 ± 15.67 years vs. 60.09 ± 13.98 years respectively (P = 0.9272). In terms of ethnicity, TNBC vs. non-TNBC patients had the following racial backgrounds: black, 58.97% vs. 39.27%; white, 35.90% vs. 57.76%; Chinese, 2.56% vs. 0.99%; others, 2.57% vs. 1.98% respectively (P = 0.004, OR = 2.755). Comparisons with respect to a history of tobacco abuse for TNBC vs. non-TNBC patients revealed a positive smoking history in 20.51% vs. 27.72% whereas there was no former or current smoking history in 71.79% vs. 61.72% respectively (P = 0.4385). Comparison of family history of a breast cancer in TNBC vs. non-TNBC patients showed that positive family history of breast cancer was seen in 30.77% vs. 33.33%, no family history of cancer was seen in 51.28% vs. 51.82% and unknown 17.95% vs. 14.85% (P = 0.8384). Pathologic stage at the time of diagnosis for TNBC vs. non-TNBC patients was as follows: stage 0, 15.79% vs. 11.37% (P = 0.4332); stage 1, 34.21% vs. 30.98% (P = 0.6890); stage 2, 28.98% vs. 37.25% (P = 0.3205); stage 3, 18.42% vs. 17.25% (P = 0.0.8591); and stage 4, 3.63% vs. 3.14% (P = 0.8651). Analysis using Chi-square test revealed χ² value of 0.855.

Conclusion: Our results add to the growing body of evidence pertaining to the association of certain demographic and clinico-pathologic characteristics in women with breast cancer. We found that in our patient population, there is a significant ethnic predisposition for the two types of breast cancers that we studied. African Americans were more likely to have TNBC compared to the higher frequency of non-TNBC in white females. We did not find a significant difference in mean age, cigarette smoking, family history and stage at diagnosis between the TNBC and non-TNBC breast cancer patients. These findings are all consistent with the previously published research studies.

Keywords: Breast cancer; Demographical differences; Non-TNBC; TNBC.