Half a century of progress against breast cancer comes down to a pair of numbers most patients never hear. "In the 1970s, the five-year survival was in the 70% range," said Dr. Alberto Montero, a medical oncologist, associate professor of medicine at the Case Western Reserve University School of Medicine, and clinical director of the Breast Cancer Medical Oncology Program at University Hospitals Seidman Cancer Center. "Now it's an upwards of 95%. And one of the key things is really early detection."
Montero wants people to take one thing from those numbers. Breast cancer is now highly curable, he said, and the progress rests on catching it early. Mammography can find small cancers, and the outcome is closely related to how early the cancer is detected.
The National Cancer Institute's SEER program reports five-year relative survival of 91.9% for women diagnosed with breast cancer between 2016 and 2022, compared with roughly 76% for women diagnosed in the mid-1970s. Survival varies sharply by how far the cancer has spread. About 64% of cases are caught while still confined to the breast, and five-year relative survival for that group is 100%, meaning those women are, on average, as likely to be alive five years later as women who never had the disease.
Based on an interview with Montero, this article from Case Western Reserve University School of Medicine examines what the screening guidelines actually cover, why most patients have no genetic cause, and how molecular testing now decides who can skip chemotherapy.
Mammography, Montero said, remains the test against which everything else is measured. "It's still the gold standard," he said. The current guidance, as he described it, is a baseline mammogram at around age 40.
His second point is the one he said gets lost. Those guidelines are written for women at average risk. A woman with a strong family history or a known genetic mutation follows a different algorithm, and her physician can help work out her actual risk.
Guidance from the major bodies has converged on 40 in recent years, though they still differ on how often to screen:
"Breast cancer is indeed not just one kind of cancer," Montero said. "I think that's another thing that a lot of people may not understand." Better science and better molecular testing, he said, have shown that breast cancer is at least four different subtypes, each treated differently and each with its own natural history.
Researchers generally group those subtypes as luminal A, luminal B, HER2-enriched and basal-like, the last of which overlaps heavily with triple-negative breast cancer, according to Susan G. Komen. Komen notes that treatment decisions are guided mainly by stage, grade, hormone receptor status and HER2 status rather than by the molecular subtype label itself, though in practice the two largely track together.
Asked who should be tested for an inherited risk, Montero started by resetting the premise. "The important thing to know is that 90% of women who have breast cancer don't have a genetic cause," he said.
Hereditary cases are a small slice of the total. About 5% to 10% of breast cancers are linked to inherited gene mutations, with BRCA1 and BRCA2 the most common. Inheriting one matters enormously for the woman who has it. More than 60% of women with a harmful BRCA1 or BRCA2 change develop breast cancer in their lifetime, compared with about 13% of women in the general population, according to the National Cancer Institute. Testing has widened accordingly. A 2024 guideline from the American Society of Clinical Oncology and the Society of Surgical Oncology recommends offering BRCA1/2 testing to every patient newly diagnosed at 65 or younger, and to selected patients over 65 based on family history, ancestry, tumor type or eligibility for specific drugs.
The same molecular tools that sorted breast cancer into subtypes are now used to decide how aggressively to treat it. "Before, we used to give chemo to almost any patient who had a tumor above a certain size," Montero said. "Now we can do genetic testing, and we can understand who has a higher risk cancer or a lower risk cancer and who needs chemotherapy, who doesn't need chemotherapy."
The evidence behind that shift came from TAILORx, a trial of 10,273 women with hormone-receptor-positive, HER2-negative, node-negative breast cancer. Researchers scored each tumor with a 21-gene assay. Among the 9,719 participants with follow-up data, 69% scored in the middle of the range, and for them, hormone therapy alone worked as well as hormone therapy plus chemotherapy, with some benefit from chemotherapy remaining for women aged 50 and younger. It was the largest breast cancer treatment trial conducted to that point, and the results were published in the New England Journal of Medicine in 2018.
For Montero, that is the direction the field is moving. "There's a lot of progress in being able to personalize a treatment for patients so that they get only the treatments that they need," he said, "and they avoid any toxic treatments that they might not need."
This story was produced by Campus Insights Media on behalf of Case Western Reserve University and reviewed and distributed by Stacker.
