STAT NEWS – Detecting cancer early in a mammogram can be life-saving.
But paradoxically, breast cancer screening also sometimes picks up tumors that would have caused less harm if they’d remained hidden.
These cases, known as “overdiagnoses,” may never go on to pose a threat to a patient’s health for a number of different reasons.
A new study, published Monday in Annals of Internal Medicine, suggests they occur in 1 of 7 breast cancer cases detected during screening.
That new estimate comes as a relief to breast cancer clinicians, who say that the study should reinforce the idea that the benefits of mammography generally outweigh its risks.
“If a clinician finds cancer on a mammogram, it often still triggers a slew of follow-up treatments possibly including biopsies, surgery, chemotherapy, and radiation — all unneeded and harmful interventions if the cancer was destined to remain silent.”
Still, experts said, it doesn’t minimize the real danger of overdiagnosis or the need to effectively communicate the risks and benefits of screening to patients.
“Honestly, [the study] is reassuring,” said Michael Hassett, an oncologist at the Dana-Farber Cancer Institute who did not work on the study.
“Most of the cases we’re finding are not overdiagnosis cases and most are true cases. The problem we’re left with is less about overdiagnosis and more about how do we tailor the intensity of treatment to intensity of cancer.”
Not all cancers will advance into invasive malignancies that spread across the body, eventually killing the patient. Some tumors will halt their progression at an early stage or grow so slowly that they’ll never pose a threat during the patient’s lifetime.
In some cases, overdiagnosis can occur because a patient will die of other causes, such as old age or existing health conditions, before even a progressive cancer can cause an issue …