Breast cancers in women younger than 50 tend to be more advanced when diagnosed. Many doctors think this is because breast cancers that develop in younger women are more aggressive and grow faster than cancers in older women.
A study looked at a different reason why breast cancers in younger women are more advanced at diagnosis. The results suggest that early-stage breast cancers in younger women are hard for screening mammograms to find. (Screening mammograms are said to have poorer sensitivity in younger women.) This means the cancers grow for more time before they're detected by mammogram. So breast cancers diagnosed in younger women are more likely to be advanced not because the cancers grow faster than cancers in older women, but because more time passes before the cancer can found by a mammogram.
The researchers used a complex math formula to analyze screening mammograms' poorer sensitivity in younger women. They found:
- most (79%) of the poorer sensitivity is because breast cancers are harder to detect in younger women; this is called lower mammographic detectability
- only 21% of the poorer sensitivity is because the cancer is growing faster (called faster tumor doubling time)
This study didn't look at why early-stage breast cancers in younger women are harder to detect. One explanation might be that younger women usually have denser breasts than older women. Dense breasts have less fatty tissue in them compared to breasts that are not dense. Cancer tumors are easier to see in a mammogram when they are surrounded by more fatty tissue.
Breast cancers in younger women may grow longer before being found by a screening mammogram. Still, annual screening mammograms starting at age 40 are the best way to diagnose breast cancer early, when it's most treatable. Depending on your unique situation, your doctor may recommend a more aggressive screening plan. Stick with the screening plan that you and your doctor have decided is the best for you.
Stay tuned to Brestcancer.org to learn about research that may help doctors develop better breast cancer screening techniques for women of all ages.