Uncommon breast tumors in perspective: Incidence, treatment and survival in the Netherlands

Abstract

The relatively small group of patients with breast tumors other than the ductal, lobular or mixed ducto-lobular types, has reached nonnegligible numbers due to the ongoing increase in the incidence of breast cancer. We investigated stage and grade distribution of uncommon breast tumors using the nation-wide Netherlands Cancer Registry (population 16.5 million) and incidence patterns, treatment and long-term survival (up to 19 years) using the regional Eindhoven Cancer Registry (population 2.4 million). Incidence of all uncommon breast tumors together was 9.2/100,000 person years (age-standardized, ESR). The proportion of stage I tumors was 70% among patients with tubular (n = 3,456) and 40–50% for mucinous (n = 3,482), papillary (n = 1,078), cribriform (n = 503) and neuroendocrine (n = 76) tumors, contrasting to 27, 28 and 36%, respectively among patients with Signet ring cell cancer (n = 75), Paget's disease (n = 818) and the common invasive ductal carcinomas (n = 121,656). A better age-, stage-, and grade-adjusted prognosis was observed for patients with lobular (death risk ratio 0.8, 95%CI: 0.7–0.9), mucinous (0.5, 0.3–0.9), medullary (0.5, 0.3–0.9) and tubular (0.4, 0.2–0.6) carcinoma or phyllodes tumor (0.02, 0.0–0.2), compared with invasive ductal carcinomas. For patients with papillary (0.6, 0.2–1.6) and cribriform (0.1, 0.0–5.1) tumors better prognosis was not statistically significant. In conclusion, histologic type was an essential determinant of survival for about 10% of all newly diagnosed women with invasive breast cancer. Because patients with mucinous, tubular, medullary and phyllodes tumors have such a good prognosis, less aggressive treatment should be considered in some cases whereby specific guidelines are becoming increasingly desirable. Communication to patients with these specific histological types should reflect this.