A new study has reported on the risk of locoregional recurrence (recurrence in the breast, chest wall, or lymph nodes) and breast cancer subtype. The study included 618 newly-diagnosed women who were treated within a single Canadian institution. Standardized methods of assessment for estrogen receptor (ER), progesterone receptor (PR), and HER2 overexpression were used for all of the patients. Study participants were grouped for analysis based on whether they had a lumpectomy or a mastectomy, as well as on their breast cancer subtype. The subtypes were defined as follows: hormone receptor positive/HER2- (ER+ or PR+ and HER2 negative), hormone receptor positive/HER2+ (ER+ or PR+ and HER2 positive), hormone receptor negative/HER2+ (ER- and PR- and HER2 positive) and triple negative (ER-, PR- and HER2 negative).

During a median follow-up period of 4.8 years, 7.5% of the women experienced a locoregional recurrence. Triple negative subtype, tumor size of 2 cm or greater, and positive lymph node status each were found to contribute to increased risk of locoregional recurrence. Among women who had lumpectomies, hormone receptor negative/HER2+ type and positive lymph node status both were found to be associated with sharply increased risk of locoregional recurrence. Among women who underwent mastectomies, triple negative subtype and positive lymph node status were associated with increased risk of locoregional recurrence. Compared to women with hormone receptor positive/HER2- tumors, both those with hormone receptor negative/HER2+ tumors treated with lumpectomy and those with triple negative disease treated with mastectomy were significantly less likely to be free of locoregional recurrence for a period of five years than other study participants. The authors conclude that different follow-up and locoregional treatment for patients with hormone receptor negative/HER2+ and triple negative subtypes might be appropriate.