A common cancer immunotherapy treatment works better for men than women, according to a new study.
The study, published in The Lancet Oncology on Wednesday, examined the effects of immune checkpoint inhibitor drugs on men and women. These drugs are “standard of care” for many cancers, according to Dr. Marcus Butler, clinical oncologist at the Princess Margaret Cancer Centre in Toronto.
They’re offered as a first-line treatment for melanoma, and a second-line treatment for lung cancer, he said.
This study found that while both men and women benefitted from the therapy, men derived a greater benefit from it. This is the first study that demonstrates a significant difference of this therapy between sexes, said study co-author Dr. Fabio Conforti, of the European Institute of Oncology in an email.
“On average, women mount stronger innate and adaptive immune responses than do men,” reads the study. This could mean that they respond to the drugs differently because of differences in their immune systems.
But there could be other reasons too, according to an attached commentary by Dr. Omar Abdel-Rahman, a fellow at the department of oncology at the University of Calgary. Although he believes that the study was overall conducted very well, he said that there could be a number of things that account for the results.
The researchers studied several types of cancers, he said, and then lumped them together for this analysis. That means that men and women could respond differently for some cancers, but not others, he said.
Also, there could be “confounding factors” that change the results.
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Smoking, for example, said Butler. “We already know that patients who are smoking have tumours that are more sensitive to immunotherapy,” he said. Women generally smoke less than men, so it’s possible that their tumours don’t respond as well to the treatment – not because of their sex, but because of their smoking habits.
Abdel-Rahman doesn’t believe that this study properly took these factors into account. Although it’s possible that the difference is due simply to sex, the information isn’t there to reach that conclusion.
“It’s a well-conducted meta-analysis. It’s hypothesis-generating. It’s thought-provoking. But it’s not practice-changing.”
“I wouldn’t recommend, and I would not personally deny one of my female patients immunotherapy for treatment of cancer just based on this study.”
Butler agrees. “There is absolutely no question that women benefit from immunotherapy. That was confirmed by this study.”
He would hate for a woman to hear about this research and decide not to undergo this therapy if it’s recommended by their doctor, because they think it won’t work for them, he said. “That would be a mistake.”
Although Conforti believes that patients’ sex should be taken into account when examining treatments, he said that further research should include more women and examine the different effects of therapy on the two sexes more closely.
“Treatment for women should not be altered based on these findings, rather we need to understand more about the mechanisms to ensure that these novel treatments can be optimized for both men and women,” he said.
Abdel-Rahman said that subsequent studies should focus on individual types of cancer and take into account possible confounding factors like smoking, in order to obtain a more accurate picture of what’s going on.