Missing the first mammogram linked to increased risk of breast cancer death, new study suggests

By Katia Hetter, CNN

(CNN) — Women who miss their first screening appointment for breast cancer could have a 40% higher long-term risk of dying from the disease, according to a new study.

I wanted to understand more about the importance of screening and the results of this large study — especially since October is Breast Cancer Awareness Month. The research, published September 24 in the journal The BMJ, involved more than 400,000 women in Sweden who were monitored for up to 25 years.

When should women begin screening for breast cancer, and why could delayed initial screening result in a higher longer-term risk of cancer death? In addition to mammograms, are there other tests that women should ask for? What about breast self-exams? And what are steps women can take to reduce their risk of developing breast cancer?

To guide us through these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore’s health commissioner.

CNN: How common is breast cancer?

Dr. Leana Wen: In the United States, breast cancer is the second most common cancer among women and the second leading cause of cancer death among women, according to the US Centers for Disease Control and Prevention. In 2022, more than 279,000 new breast cancer cases in female patients were reported in the US; in 2023, more than 42,000 women died from the disease.

A report published in February found that globally, 1 in 20 women will be diagnosed with breast cancer in their lifetime. At this rate, researchers estimate that by 2050, there will be 3.2 million new breast cancer cases and 1.1 million breast cancer-related deaths per year.

Early screening is crucial because the best prognosis is when breast cancer is diagnosed and treated in its earliest stages. When breast cancer is diagnosed in its localized stages — before it has spread — the five-year survival rate is more than 99%, according to the American Cancer Society. When the cancer is detected after it has spread to other organs, the survival rate drops to about 32%.

CNN: When should women begin screening for breast cancer?

Wen: Last year, the US Preventive Services Task Force lowered the recommended age for most women to start receiving mammograms to age 40. The guidance is that women should receive a mammogram every other year until age 74. For those 75 and above, the decision to continue screenings is a personal one to make with one’s primary care provider.

This recommendation covers people with an average risk of breast cancer. Those with a higher risk are encouraged to speak with their health care provider to discuss whether they should begin screenings sooner and at a higher frequency than every other year. Elements that increase risk include a history of radiation to the chest, certain genetic mutations, and having a first-degree relative (like a mother or sister) with breast cancer.

CNN: What does this new study show?

Wen: This study tracked outcomes from 432,775 women in Sweden for up to 25 years. Among women invited to their first mammogram screening, nearly one-third did not participate. The nonparticipants continued to be less likely to participate in subsequent mammograms and more likely to have breast cancer diagnosed in advanced stages, the researchers found.

Notably, the odds of these initial nonparticipants being diagnosed with stage 3 cancer was 1.5 times greater, and 3.6 times greater for stage 4 cancer, compared with those who did participate in a first screening. Breast cancer deaths after 25 years for this group were significantly higher compared with those who followed through on a first mammogram.

These results are notable because of the large population that the study team monitored over a substantial period of time. Researchers point out that findings may not generalize to all populations that have different health care systems from Sweden’s, though I think that the concept of perpetually missed screenings leading to higher cancer rates probably is the case around the world. An accompanying editorial in the same journal highlighted that the decision to attend the first mammography screening is not just a short-term health check-up — it’s a long-term investment that has implications for future health and survival.

CNN: Why does delayed initial screening result in a higher longer-term risk of cancer death in this study?

Wen: I think the key is that the initial nonparticipants were also more likely to persistently miss subsequent follow-up screening exams. The reasons for this are likely complicated and could be a combination of factors, including lack of awareness, barriers to access and fear of finding out the result. Cultural factors may also be at play. The result is that these individuals were more likely to have their cancers diagnosed at a later stage, when survival rates are lower, and therefore tragically ended up having more deaths from their cancers.

CNN: In addition to mammograms, are there other tests that women should ask for?

Wen: Mammograms, which are essentially an X-ray of the breast, are the standard screening test for most women at average risk of breast cancer. Those with higher risk of breast cancer may be recommended for additional tests, such as genetic testing, breast MRI or ultrasound. Women with dense breast tissue may also wish to ask their provider if additional tests are recommended, since the mammogram is less sensitive in detecting breast cancer in these individuals.

CNN: What about breast self-exams?

Wen: Breast self-exams are not routinely recommended as a screening test and should not replace the mammogram. However, women should know how their breasts look and feel and be on the lookout for any concerning changes.

It is important to separate out screening from diagnosis. The mammogram is a screening test that is done when someone has no symptoms. But if someone detects a new mass or lump, they need to get it evaluated to see whether it could be cancer.

Other potentially concerning changes including nipple discharge, pain or swelling in their breast, changes in the color of the nipple or breast, the nipple turning inward, painful or enlarged lymph nodes in the armpits or near the collarbone, or redness or flaky skin on the breast. People who notice these changes should not wait to make an appointment to see their health care provider.

CNN: For women who are concerned about their risk of breast cancer, are there steps they can take to reduce their risk?

Wen: Yes. Risk factors for developing breast cancer include smoking, heavy alcohol use, overweight and obesity. Quitting smoking, reducing alcohol consumption and keeping a healthy weight will help to reduce the risk of breast cancer. Being physically active and eating a nutritious diet can also reduce cancer risk, as well as improve health overall.

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