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Year in Review: Early Breast Cancer

— USPSTF screening recommendations, broader indication for ribociclib, OS win for pembrolizumab

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 2024 YEAR IN REVIEW EARLY BREAST CANCER over a computer rendering of breast cancer.

News in early breast cancer this year was marked by updated U.S. Preventive Services Task Force (USPSTF) screening recommendations, a new CDK4/6 inhibitor approval for the adjuvant setting, and declines in recurrence rates amid improvements in care.

USPSTF Breast Cancer Screening Recs

In April, the USPSTF finalized new breast cancer screening recommendations that suggest women at average risk for breast cancer should start screening at the age of 40.

The Task Force now recommends mammography every other year from ages 40 to 74 years -- a change from the that recommended biennial screening starting at age 50, with individual decision making for women in their 40s.

The change brings the USPSTF's recommendations more in line with current clinical practice and with guidelines from other leading societies, including the American College of Radiology and Society of Breast Imaging, both of which recommend annual screening starting at age 40.

The American Cancer Society recommends that all women should be given the opportunity to be screened at age 40, recommends annual screening at age 45 and then biennial screening at age 55, with the option to continue screening annually.

Ribociclib Approval Extended to Early Breast Cancer

In September, the FDA approved ribociclib (Kisqali) in combination with endocrine therapy as adjuvant treatment for early high-risk breast cancer.

Previously approved in the metastatic setting, the CDK4/6 inhibitor is now also indicated for patients with stages II-III disease who have hormone receptor (HR)-positive/HER2-negative tumors and a high risk for recurrence following surgery, including node-negative (N0) disease.

Approval was based on results from the NATALEE trial, which involved more than 5,100 patients with early-stage breast cancer who received 3 years of adjuvant treatment with ribociclib plus a non-steroidal aromatase inhibitor for at least 5 years. That trial showed that ribociclib plus the aromatase inhibitor reduced the risk of disease recurrence by 25% versus an aromatase inhibitor alone, with rates of invasive disease-free survival (iDFS) at 3 years of 90.7% and 87.6%, respectively (HR 0.749, 95% CI 0.628-0.892, P=0.0006).

Updated data from the phase III trial suggested an even more favorable iDFS benefit (HR 0.715, 95% CI 0.609-0.840, P<0.0001).

An OS Win for Pembrolizumab in Early TNBC

PD-1 inhibition before and after surgery for high-risk, early triple-negative breast cancer (TNBC) led to significant improvement in overall survival (OS), according to updated results from the KEYNOTE-522 trial.

At a median follow-up of 75 months, 5-year OS -- a principal secondary endpoint of the trial -- was 86.6% in patients who received pembrolizumab (Keytruda) before and after surgery compared with 81.7% in those who received only neoadjuvant chemotherapy. That survival advantage extended across most prespecified subgroups, including by PD-L1 expression status, nodal status, and tumor size.

Patients benefited from pembrolizumab regardless of whether they achieved a pathologic complete response (pCR), reported Peter Schmid, MD, PhD, of Barts Cancer Institute and Queen Mary University in London, at the European Society for Medical Oncology congress in Barcelona.

KEYNOTE-522 included 1,174 patients with newly diagnosed stage II or III TNBC. All patients received neoadjuvant chemotherapy with carboplatin-paclitaxel followed by doxorubicin or epirubicin plus cyclophosphamide.

The trial had met the dual primary endpoints of pCR (64.8% with pembrolizumab vs 51.2% without it) and event-free survival (EFS) at 3 years (84.5% vs 76.8%). An updated analysis showed a continued EFS advantage with pembrolizumab at 5 years (81.2% vs 72.2%).

Early Breast Cancer Recurrence

A decades-long analysis of clinical trial data showed that the long-term risk of distant recurrence in women with early breast cancer has significantly declined.

In women with estrogen receptor (ER)-positive disease scheduled for at least 5 years of endocrine therapy, the 10-year rate of distant recurrence declined from 20.5% for those enrolled in trials in 1990-1999 to 15.4% in 2000-2004 and 11.7% in 2005-2009. For ER-negative disease, rates declined from 29.7% in 1990-1999 to 21.5% and 18.2%, respectively, according to a report from Early Breast Cancer Trialists' Collaborative Group published in .

The authors cited a number of possible explanations for the decline in distant recurrences, including the growing proportion of patients with node-negative disease in trials, better tumor staging, and improvements in adjuvant treatment.

Another study -- a long-term follow-up of the Scottish Breast Conservation Trial -- found that the benefits of adjuvant radiotherapy (RT) for early breast cancer was limited to the first 10 years after treatment.

That report found that at a median follow-up of 17.5 years, patients treated with adjuvant RT had a 61% lower risk of ipsilateral recurrence. However, that difference was driven by a 76% reduction in the hazard ratio (HR) during the first 10 years. Thereafter, the risk of ipsilateral recurrence was similar between patients who did and did not receive adjuvant RT.

OS was comparable between the two groups, reported Linda Williams, PhD, of the University of Edinburgh in Scotland, and co-authors in .

"The results can help clinicians to advise patients better about their choice to have radiotherapy or not if they better understand what benefits it does or does not bring," the authors wrote of their findings.

Other Newsworthy Developments in 2024

FDA Panel Backs Cryoablation in Early Breast Cancer as Alternative to Surgery

Study: Avoid Completion ALND for Abemaciclib Eligibility in Early Breast Cancer

Benefits of Neoadjuvant Immunotherapy in Breast Cancer Extend Beyond TNBC

Lymphedema Risk No Higher With 3-Week RT Regimen in Early Breast Cancer

More Evidence Favors a Shorter Course of Post-Mastectomy RT

Bilateral Mastectomy Reduces Contralateral Breast Cancer Risk, but Not Mortality

EHR 'Nudge' Cut Low-Value Surgery Rates in Older Breast Cancer Patients

Acupuncture Reduced Hot Flashes Related to Endocrine Therapy for Breast Cancer

Docetaxel Tied to Less Taxane Neuropathy in Black Breast Cancer Patients

FDA Greenlights Imaging Agent to Detect Residual Cancer After Lumpectomy

'Excellent' Outcomes After Complete Response in Lymph Node-Positive Breast Cancer

In TNBC, Pathologic Complete Response May Vary by Race/Ethnicity

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    Mike Bassett is a staff writer focusing on oncology and hematology. He is based in Massachusetts.