Breast cancer that is HER2-positive is associated with a greater risk of recurrence. Treatment for HER2-positive breast cancer tumours larger than a centimetre or have progressed to lymph nodes is challenging. According to the research, the conventional treatment for early-stage is a 12-month course of trastuzumab in combination with chemotherapy after surgery. However, the benefit of adjuvant (post-operative) trastuzumab treatment for smaller HER2-positive cancers is not well-known. This is true for cancer that has not migrated beyond the primary location (metastasized) to lymph nodes.
A recent study has shed some light on the condition. The team stated that treating women with one type of early-stage breast cancer with the Monoclonal Antibody trastuzumab after surgery decreases the risk of the tumour returning.
To arrive at a conclusion, the team investigated all Saskatchewan women diagnosed with small HER2-positive breast cancer between January 2008 and December 2017. HER2 breast cancer is named after the protein human epidermal growth factor receptor two that malfunctions to induce fast cancer cell development.
Researchers found 91 patients with HER2-positive breast tumours that were less than 10 millimetres in size. Overall, 39 patients with tumours greater than 5mm were given adjuvant trastuzumab and chemotherapy. On the other hand, 52 patients with smaller tumours were not given post-operative trastuzumab.
The research revealed that women with HER2 positive tumours that were less than one centimetre in size and were node-negative had a low recurrence rate. Moreover, those who received adjuvant trastuzumab, on the other hand, had a further drop in the chance of recurrence. Women who did not get adjuvant trastuzumab, for example, had a four-fold increased risk of recurrence.
After ten years, 97 per cent of women in the trastuzumab group had no recurrence of breast cancer, compared to 88 per cent of those who did not get the treatment.
According to the group, the analysis of this retrospective cohort study was statistically adjusted. Thus, it accounts for factors such as patient ages and other hazards to make the findings as near to those of a randomized study.
They believe that the study's findings, which support adjuvant trastuzumab for small tumours, will lead to more frequent use of the drug, minimizing the risk of cancer recurrence in younger women with tumours larger than 5mm.
However, the treatment toxicity is a significant concern when considering the use of adjuvant trastuzumab. Hence, a key topic to address is whether the duration of treatment should be reduced from the current 12 months to six months.