Health Rounds: Breastfeeding is safe for breast cancer survivors

By Nancy Lapid

(Reuters) - Hello Health Rounds Readers! Today we highlight research findings reported at ESMO 2024, the annual meeting of the European Society of Medical Oncology. Two studies have shown for the first time that breastfeeding after treatment for breast cancer does not increase a woman's recurrence risk. And, as other studies at the meeting showed, immunotherapy continues to improve hopes for long-term survival for people with various types of cancer.

Breastfeeding found to be safe after breast cancer treatment

Breastfeeding is safe for women who have been treated for breast cancer, two large studies have shown for the first time.

Even cancer survivors at higher genetic risk do not face an increased risk of recurrence or development of new breast cancers if they choose to breastfeed, researchers reported at the European Society of Medical Oncology (ESMO) meeting in Barcelona.

One study of nearly 5,000 young breast cancer survivors carrying a high-risk BRCA gene mutation identified 474 who subsequently gave birth, one in four of whom breastfed their baby. Just under half were unable to breastfeed because both breasts had been removed to reduce future cancer risk. After a median follow-up of seven years from giving birth, there was no difference in the number of breast cancer recurrences, new breast cancers or overall survival in women who breastfed compared to those who did not.

"With this new information, we can debunk the myth that breastfeeding is neither possible nor safe for breast cancer survivors," Dr. Fedro Alessandro Peccatori of the European Institute of Oncology IRCCS in Milan, who worked on the study, said in a statement. "They can have a normal pregnancy and relationship with their baby, including breastfeeding."

A second study included 518 women who temporarily interrupted their breast cancer treatment to have a baby. Of those, 317 had at least one baby and 62% of them breastfed. At two years from the first live birth, the proportion of women with breast cancer recurrence or new breast cancer was similar in those who breastfed (3.6%) and those who did not (3.1%).

Other recent studies have shown that neither assisted-reproduction treatments nor pregnancy itself are associated with increased risk of recurrence or new cases of breast cancer.

Immunotherapy improves outcomes in gynecological cancers

Adding Merck's immunotherapy drug Keytruda to current standard treatments for gynecological cancers can provide meaningful benefits for certain patients, researchers reported at the ESMO 2024 meeting in Barcelona.

In a late-stage trial in women with high-risk locally advanced cervical cancer, adding Keytruda to chemoradiotherapy achieved a three-year overall survival rate of 82.6%, compared to 74.8% in patients who received chemoradiotherapy plus a placebo.

"The benefit in terms of improved overall survival should change our practice as soon as possible," said Dr. Isabelle Ray-Coquard, president of the Group d'Investigateurs National Evaluation des Cancers de l'Ovaire (GINECO) based in Lyon, France, who was not involved in the research.

"Immunotherapy plus chemoradiotherapy provides a new standard of care for patients with high-risk locally advanced cervical cancer," Ray-Coquard said in an ESMO statement.

A second late-stage trial in women with newly diagnosed high-risk endometrial cancer found that adding Keytruda to chemotherapy after surgery did not improve disease-free survival for everyone, but it did show a meaningful disease-free survival benefit for patients whose tumors showed a genetic abnormality known as deficient mismatch repair (dMMR).

"Although this trial is not positive in the study population as a whole, it gives us important information indicating that patients with endometrial dMMR tumors are more sensitive and reactive to immunotherapy," Dr. Elene Mariamidze of the Georgian School of Oncology in Tbilisi, who was not involved in the study, said in the ESMO statement.

Immunotherapy helpful in skin, breast, bladder cancers

Immunotherapy can also prolong survival in patients with advanced melanoma, hard-to-treat breast cancer and advanced bladder cancer, researchers reported at ESMO 2024 in Barcelona.

"The main message from all of these studies is that immunotherapy continues to keep its promise and hope of long-term survival for many patients with different types of cancer," Dr. Alessandra Curioni-Fontecedro, director of oncology at the Hospital of Fribourg, Switzerland, who was not involved in the study, said in a statement.

In one late-stage trial involving patients with advanced melanoma, half of the participants received immunotherapy with a combination of Opdivo and Yervoy, both from Bristol Myers Squibb. More than half of those were still alive six years later. A good initial response to the treatment – that is, no disease progression for at least three years – predicted a good long-term outcome: 96% of such patients were still alive at 10 years.

"The results from this trial do confirm the potential for cure with immunotherapy in patients with advanced melanoma," Dr. Marco Donia of the Copenhagen University Hospital Herlev, who was not involved in the research, said in a statement.

"For patients who show no disease progression beyond three years, these longer-term results demonstrate that most of them never progress," Donia added. "The melanoma-specific survival is very high in this group of patients."

Immunotherapy also boosted survival in patients with early-stage triple-negative breast cancers, which fail to respond to commonly used breast cancer treatments. Overall survival at five years was 86.6% with Keytruda plus chemotherapy before surgery and continued immunotherapy after surgery, compared to 81.2% with chemo and surgery alone, the study found.

"We had thought that breast cancer may not be sensitive to immunotherapy alone but giving it in combination with chemotherapy before surgery and then further afterwards improves overall survival in many patients," Curioni-Fontecedro said.

A similar improvement in overall survival with giving immunotherapy before surgery was seen in a late-stage study of patients with muscle-invasive bladder cancer. Patients treated with Astra Zeneca's Imfinzi plus chemotherapy before radical cystectomy followed by continued Imfinzi had significantly longer event-free survival and overall survival compared to those receiving chemotherapy alone.

(Reporting by Nancy Lapid; editing by Will Dunham)