Effect of adjuvant chemotherapy in postmenopausal patients with invasive ductal versus lobular breast cancer

Abstract

On the basis of the lack of response of invasive lobular breast cancer to neoadjuvant chemotherapy, we questioned the effectiveness of adjuvant chemotherapy in relation to histology. Women with primary nonmetastatic invasive ductal or (mixed type) lobular breast cancer, aged 50-70 years, diagnosed between 1995 and 2008, were selected from the Netherlands Cancer Registry and followed until January 1, 2010. The patients were divided in two groups: one group receiving adjuvant hormonal therapy only and the other receiving adjuvant hormonal therapy in combination with adjuvant chemotherapy. In total, 19,609 patients had ductal cancer and 3685 had lobular cancer. The 10-year overall survival rate in ductal cancer when treated with hormonal therapy alone was 69%, compared with 74% with the combination therapy (P < 0.0001). In lobular cancer, 10-year survival rates were 68% after hormonal treatment alone and 66% after the combination therapy (P = 0.45). The hazard ratio (HR) for mortality in ductal cancer after combination therapy was 0.70 [95% confidence interval (CI) 0.64-0.76; P < 0.0001], compared with hormonal treatment alone. The HR in lobular cancer was 1.00 (95% CI 0.82-1.21; P = 0.97). Adjuvant chemotherapy seems to confer no additional beneficial effects in postmenopausal patients with pure or mixed type lobular breast cancer receiving hormonal therapy.