Does triple negative breast cancer influence your decision to boost an older patient post lumpectomy?

Yes. The phenotype of breast cancer does predict the risk of relapse in the elderly population as well. For that reason, we would offer a boost in all triple negative patients, irrespective of age. In a recent update of the Toronto–British Columbia (TBC) randomized study for older patients with node-negative breast cancer comparing tamoxifen or tamoxifen and breast RT, intrinsic subtype was noted to be prognostic for ipsilateral breast tumor recurrence (10-year estimates: luminal A, 5.2%; luminal B, 10.5%; high risk, 21.3%).

Yes. The pathologic subanalysis of the EORTC boost trial clearly demonstrated a more substantial benefit from a tumor bed boost in patients with high grade disease. I think it is reasonable to extrapolate this finding to indicate that a boost is likely to be beneficial in triple negative disease, as most of these tumors are high grade.

In addition, the exploratory analyses of the Danish Breast Cancer Group 82b and 82c trials suggested that patients who received PMRT experienced a significantly higher risk of local-regional recurrence if they had triple negative disease compared to ER positive disease. I believe this is indirect evidence that triple negative disease is more radioresistant, and thus provides reasonable justification for dose escalation in this molecular subtype.