Women with mucinous or tubular/cribriform breast cancer had better outcomes than those with other histotypes in the monotherapy cohort of the BIG 1-98 trial, according to an article printed online ahead of print in the Annals of Oncology.1
Investigators studied the outcomes of postmenopausal women with hormone receptor-positive, early breast cancer with special histotypes (mucinous, tubular, or cribriform) enrolled in the monotherapy cohort (5 years with tamoxifen or letrozole) of the BIG 1-98 trial.
The cohort included 4,922 women, of whom 4,091 had central pathology review. Histotype groups were defined as mucinous (n=100), tubular/cribriform (n=83), ductal (n=3,257), and other (n=651). Of the 183 women with mucinous, tubular/cribriform tumors, 96 were randomly assigned to receive letrozole and 87 to tamoxifen.
At a median follow-up of 8.1 years, patients with tubular/cribriform breast cancer had the best outcomes in disease-free survival, overall survival, breast cancer-free interval (BCFI), and distant recurrence-free interval (DRFI) compared with all other histotypes.
Results showed that those with the tubular/cribriform histotype had a 5-year BCFI of 97.5% compared with 93.5% (mucinous), 88.9% (ductal), or 89.9% (other). Five-year DRFI rates were 97.8% in those with tubular histotype and 98.8% in cribriform, 90.9% in ductal, and 92.1% in other.
“Within the subgroup of women with special histotypes, we observed a non-significant increase in the hazard of breast cancer recurrence with letrozole (HR [letrozole vs tamoxifen]: 3.31, 95% CI: 0.94-11.7; P=0.06),” the authors wrote.
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Although women with the mucinous or tubular/cribriform histotypes of breast cancer had a better outcome in this study, the observation was based on a limited number of events, authors cautioned. The magnitude of the letrozole advantage may not be as large in patients with mucinous or tubular/cribriform disease in this patient population.
- Munzone E, Giobbie-Hurder A, Gusterson BA, et al. Outcomes of special histotypes of breast cancer after adjuvant endocrine therapy with letrozole or tamoxifen in the monotherapy cohort of the BIG 1-98 trial. [published online ahead of print September 19, 2015]. Ann Oncol. doi: 10.1093/annonc/mdv391.