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

BACKGROUND: 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. PATIENTS AND METHODS: 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. RESULTS: 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). CONCLUSION: Adjuvant chemotherapy seems to confer no additional beneficial effects in postmenopausal patients with pure or mixed type lobular breast cancer receiving hormonal therapy.