Trending Clinical Topic: Breast Cancer

Ryan Syrek


October 01, 2021

Each week, we identify one top search term, speculate about what caused its popularity, and provide an infographic on a related condition. If you have thoughts about what's trending and why, share them with us on Twitter or Facebook.

A slew of significant studies released just prior to the start of October, Breast Cancer Awareness Month, resulted in this week's top trending clinical topic. Data have long shown that women with schizophrenia have a higher risk for breast cancer. A Finnish study, published in The Lancet on August 30, examined a registry of more than 30,000 women with schizophrenia. The findings may shed light on a cause behind the increased risk in this population (see Infographic below).

Unlike with prolactin-increasing antipsychotics, the use of prolactin-sparing antipsychotics was not significantly associated with a greater risk for breast cancer. At least one expert says that clinical implications are premature at this point. However, study co-author Christoph Correll, MD, told Medscape, "In case of planning for long-term antipsychotic [therapy], prefer non-prolactin-raising antipsychotics in females and inform patients about a potential risk to allow for informed shared decision-making."

A separate, population-based study recently found that women with breast or ovarian cancer and BRCA1/2 or other pathogenic gene variants may be equally as likely or less likely than non-carriers to die from their cancer in the short term. As reported in the Journal of the National Cancer Institute on August 9, researchers analyzed data from more than 22,000 patients with breast cancer and 4300 patients with ovarian cancer. In triple-negative breast cancer (TNBC), cancer-specific mortality was significantly lower with BRCA1 (hazard ratio [HR], 0.49) and BRCA2 (HR, 0.60). In patients with ovarian cancer, cancer-specific mortality was also significantly lower with BRCA2 (HR, 0.35) and genes that were not BRCA1/2 (HR, 0.47). The researchers found no pathogenic variant linked with higher cancer-specific mortality.

More encouraging findings from other studies were reported at the European Society for Medical Oncology (ESMO) Annual Meeting 2021. The results of a trial involving trastuzumab deruxtecan (Enhertu) in the second-line treatment of metastatic HER+ breast cancer were called "phenomenal," "astonishing," and "practice-changing" In a head-to-head trial against the current standard of care, trastuzumab emtansine (T-DM1, Kadcyla), trastuzumab deruxtecan won hands down. The median progression-free survival  with trastuzumab deruxtecan was 25.1 months, compared with 7.2 months with T-DM1 (HR, 0.26). The data have convinced some to already call for a change to recommendations.

Also at ESMO, results of a longer-term study on chemotherapy among women with metastatic TNBC showed a survival benefit from adding the immune checkpoint inhibitor pembrolizumab (Keytruda) in a subgroup of women. For women whose tumors had a combined positive score for PD-L1 expression of ≥ 10, this combination is the new standard of care, say experts. After a median follow-up of 44 months, the median overall survival was 23 months with pembrolizumab added to chemotherapy, compared with 16.1 months for chemotherapy alone. This translated into an HR for death with the combination of 0.73 (P = .0093).

The long-term follow-up results of the phase 3 randomized BrighTNess trial were also presented at ESMO. The initial improvement that was seen in pathologic complete response  rates with the addition of carboplatin to paclitaxel and standard neoadjuvant chemotherapy translated into improved event-free survival  rates in patients with resectable TNBC more than 4 years after surgery. The benefits of adding carboplatin to paclitaxel, followed by four cycles of AC (doxorubicin and cyclophosphamide) chemotherapy, were seen in patients with germline BRCA mutations as well as in those with wild-type BRCA. However, the trial results also showed no short- or long-term benefits to adding veliparib (ABT-888), a poly (ADP-ribose) polymerase (PARP) inhibitor, to the mix.

Finally, also at ESMO, a UK individual patient data analysis of five major trials showed that adjuvant trastuzumab (Herceptin, Roche) can be safely given to patients with HER2+ early breast cancer for 6 rather than 12 months, with no impact on treatment efficacy. The combined data included more than 11,000 patients who were treated with trastuzumab for 9 weeks or 6 months vs the current standard of 12 months. The findings showed that treating patients with HER2+ early breast cancer for 6 months was noninferior to continuing treatment for 12 months, with no significant difference in 5-year invasive disease-free survival (IDFS) rates. However, when 9 weeks of trastuzumab was compared with 12 months, the IDFS rates were lower with the shorter duration of treatment and over the prespecified noninferiority limit, indicating that it did not perform as well.

From a worrisome association with certain drugs to encouraging survival and treatment findings, Breast Cancer Awareness Month kicked off with a host of important studies, leading to this week's top trending clinical topic.

Read more clinical information on breast cancer.


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