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Adjuvant chemotherapy demonstrates survival benefit in triple-negative breast cancer subtype
CHICAGO — Patients with small, node-negative, triple-negative breast cancer treated with adjuvant chemotherapy experienced improvements in OS and breast cancer specific-survival, according to a study presented at ASCO.
“International guidelines differ in their recommendation for adjuvant chemotherapy in small, node-negative, triple-negative breast cancer,” Tessa Gerjanne Steenbruggen, MD, of the department of medical oncology at the Netherlands Cancer Institute and colleagues wrote. “We evaluated associations of chemotherapy with long-term outcome in a large, population-based, triple-negative breast cancer cohort.”
Steenbruggen and colleagues used the Netherlands Cancer Registry to identify 4,393 patients who received a diagnosis of pT1N0M0 triple-negative breast cancer between 2005 and 2015, 284 of whom had T1a, 924 had T1b and 3,185 had T1c tumors.
The researchers documented patient, tumor and therapy traits. Data from Statistics Netherlands were used to determine date and cause of death. They also performed multivariable Cox regression models to assess how chemotherapy affects OS and breast cancer-specific survival while adjusting for baseline characteristics. Tumor size and grade were considered in subgroup evaluations.
Approximately half (53%) of patients received chemotherapy. When stratifying by tumor grade, 6% of patients with T1a, 17% with T1b and 67% with T1c tumors received chemotherapy.
Use of chemotherapy rose throughout the study period and fluctuated by geographic region. Patients who were administered chemotherapy were more likely to be younger, have bigger tumors, have a greater tumor grade and have more isolated tumor cells in the lymph nodes.
A total of 611 patients died during a median follow-up period of 7 years (interquartile range, 5-10 years). Breast cancer was the cause of death in 287 patients.
Overall, patients treated with chemotherapy demonstrated increased OS (adjusted HR = 0.55; 95% CI, 0.44–0.69). OS also improved with chemotherapy administration in patients with T1c (adjusted HR = 0.53; 95% CI, 0.41-0.67) and grade 3 (adjusted HR = 0.5; 95% CI, 0.39-0.65) tumors. There was no significant association between OS and chemotherapy in patients with T1a, T1b or grade 1 or 2 tumors. The relationship between chemotherapy and breast cancer-specific survival was similar to the OS outcomes.
“Adjuvant chemotherapy is associated with higher OS and breast cancer-specific survival in small, node-negative, triple-negative breast cancer,” Steenbruggen and colleagues concluded. “Benefit is most evident in grade 3 tumors and tumors greater than 1 cm and not evident in tumors less than or equal to 1 cm and grades 1 to 2.” – by Alaina Tedesco
Reference:
Steenbruggen TG, et al. Abstract 536. Presented at: ASCO Annual Meeting; May 31-June 4, 2019; Chicago.
Disclosure: Steenbruggen reports no relevant financial disclosures. Please see abstract for all other authors’ relevant financial disclosures.
Perspective
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The investigators from the Netherlands conducted this very important study that used a population-based cancer registry to examine the impact of adjuvant chemotherapy in patients with small, node-negative, triple-negative breast cancers. The cohort included almost 4,500 patients.
What they found was very interesting — clinical outcomes were improved with the administration of adjuvant chemotherapy in patients who had T1c high-grade tumors. Additionally, there was a worsening of clinical outcomes in patients with T1a and/or T1b low or intermediate grade tumors, suggesting that we might actually be harming those patients with lower risk triple-negative breast cancer if we administer adjuvant chemotherapy.
In this era where we are trying to treat patients more safely by personalizing management and de-escalating therapies, this is a very important study. As physicians, we need to step back and properly consider all the clinical and pathological characteristics of patients and their cancers before recommending treatments. The take home message from this study is that, some patients with very small node-negative and low or intermediate grade triple-negative breast cancers may safely omit chemotherapy.