A vaccine for breast cancer?

Cancer researchers are hailing an "exciting step forward" in the war on cancer: A new vaccine that seems to help the immune system fight metastatic breast and ovarian cancer. Nearly 40,000 breast cancer patients and more than 15,000 ovarian cancer patients are killed each year in America. But that could change if the preliminary findings of a new study are to be believed. Here's what you should know:

How was the study conducted?

Researchers from the Center for Cancer Research, the National Institutes of Health, and the National Cancer Institute gave monthly shots to 26 women struggling with late-stage cancer. The women had already had surgery and several rounds of radiation or chemotherapy, but were still plagued by disease.

Subscribe to The Week

Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.

SUBSCRIBE & SAVE

Sign up for The Week's Free Newsletters

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

Sign up

How does the vaccine work?

The injection, called Panvac, consists of normal cells "that have been modified by adding viruses that code for proteins associated with cancer cells," says Kim Carollo at ABC News. Once those proteins are in the body, the immune system can more easily flag harmful cancer cells, and then attack them.

What happened to women who received the vaccine?

The spread of tumors to other parts of the body slowed way down. In one woman, the cancer became untraceable altogether. This is quite "promising," says Alice Park at TIME. "Among the 12 breast cancer patients, the median time before they saw any progression of the disease was 2.5 months, and the median survival was over one year." For women with ovarian cancer, "the overall survival was slightly longer, at 15 months." Researchers believe these women would have died much sooner had they not been given Panvac.

And this has researchers excited?

Yes. The vaccine has other uses besides tacking on extra months to the life of a patient who has "exhausted other forms of treatment" — it could also treat early stage cancers, says Maureen Salamon at USA Today. Researchers hope that giving Panvac to women as soon as they're diagnosed would slow the spread of the disease — offering a much longer window in which other treatments might snuff out the cancer.

Sources: ABC News, TIME, USA Today