Treating early-stage, HER2-positive breast cancer with adjuvant trastuzumab plus chemotherapy results in long-term benefits, including a reduced risk of recurrence and breast cancer-related mortality, according to a meta-analysis published in The Lancet Oncology.

Although clinical trials have shown that adding trastuzumab to chemotherapy can improve outcomes, “it was unclear how the level of HER2 amplification, tumor characteristics (eg, estrogen receptor status), or other patient factors influence the magnitude and duration of benefit,” the study authors wrote.

To gain some insight, they conducted a meta-analysis of 7 randomized, controlled trials enrolling a total of 13,864 patients. The trials were designed to compare adjuvant trastuzumab plus chemotherapy with chemotherapy alone.

The mean treatment duration was 14.4 months, and the median follow-up was 10.7 years.

Compared with chemotherapy alone, trastuzumab plus chemotherapy resulted in a significant decrease in breast cancer recurrence (rate ratio [RR], 0.66; 95% CI, 0.62-0.71; P <.0001) and breast cancer-related mortality (RR, 0.67; 95% CI, 0.61-0.73; P <.0001).

The absolute 10-year recurrence risk was reduced by 9%, the 10-year risk of breast cancer mortality was reduced by 6.4%, and the all-cause mortality risk was reduced by 6.5% with the addition of trastuzumab.

There was no significant difference in risk reduction for recurrence between estrogen receptor-positive or -negative tumors or other histopathologic features. There was also no difference when trastuzumab was administered concurrently or sequentially with chemotherapy.

The reduction in risk of recurrence was greatest during the first year after treatment (RR, 0.53; 99% CI, 0.46-0.61), with a smaller reduction between years 2 and 4 (RR, 0.73; 99% CI, 0.62-0.85), and years 5 and 9 (RR, 0.80; 99% CI, 0.64-1.01).

“[T]his meta-analysis confirms that breast cancer recurrence and mortality can be reduced by a third by adding 1 year of trastuzumab treatment to adjuvant chemotherapy in patients with early-stage, HER2-positive breast cancer,” the study authors concluded.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Early Breast Cancer Trialists’ Collaborative group. Trastuzumab for early-stage, HER2-positive breast cancer: A meta-analysis of 13 864 women in seven randomised trials. Lancet Oncol. 2021;22:1139-1150. doi:10.1016/S1470-2045(21)00288-6