Researchers set out to investigate the association between adjuvant chemotherapy and outcomes in patients with small, node-negative, triple-negative breast cancer (TNBC) and found that whereas adjuvant chemotherapy was associated with increased overall survival (OS) in older patients with pT1b tumors, younger patients with pT1a tumors experienced higher rates of mortality.
For this observational study, results of which are published in JAMA Oncology, 16,180 patients from the National Cancer Database met study criteria. Of the study population, 9,498 participants did not receive chemotherapy while 6,682 did. After a median follow-up of 41.6 months, the scientists concluded that patients with pT1a tumors and patients aged 50 years or younger fared worse with chemotherapy and experienced worse mortality compared with those patients who are 75 years or older and who have pT1b tumors.
The researchers believe patients who are older than 75 with pT1b tumors who were treated with chemotherapy may have a better OS than patients who are younger than 50 years with pT1a tumors because pT1b tumors have a 5-year distant reoccurrence of up to 10%.
Further research is needed to discover why mortality is worse for patients younger than 50 years with pT1a tumors compared with patients older than 75 with pT1b tumors; however, the researchers predict this is because of the toxic effects of chemotherapy outweighing its benefits for pT1a tumors and because younger patients tend to receive chemotherapy for a more aggressive tumor biology.
Study authors, led by Oluwadmilola T. Oladeru, MD, MA of the Harvard Radiation Oncology Program at Massachusetts General Hospital, concluded, "Pertinent variables, such as performance status, tumor reoccurrence, and toxicity, were unavailable in the National Cancer Database, resulting in unmeasured confounding despite matching. Nevertheless, as there are favorable outcomes regardless of chemotherapy use and given the risk of worsened mortality, the avoidance of chemotherapy may be considered for those younger than 50 years and with pT1a TNBC."
For More Information
Oladeru OT, Singh AK & Ma SJ (2020). Association of adjuvant chemotherapy with overall survival among women with small, node-negative, triple-negative breast cancer. JAMA Netw Open, 3(9):e2016247. DOI:10.1001/jamanetworkopen.2020.16247
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