Top Line: While we continually escalate care for more aggressive subtypes of breast cancer, efforts to de-escalate treatment for indolent varieties continue in full force.
The Study: So much so that some now suggest low-risk DCIS should receive active surveillance akin to low-risk prostate cancer. The prospective non-inferiority COMET trial randomized 957 women with newly-diagnosed low-risk (read: grade 1-2, ER/PR >10%, HER2-negative) DCIS to standard care (n=473) versus active surveillance (n=484) with mammography q6 months. In the surveillance arm, biopsies were performed for suspicious clinical or radiographic changes and treatment recommended only upon histologic confirmation of invasive disease. This all seems pretty straightforward so far, but wait. The “active monitoring” group could receive endocrine therapy per patient/physician preference, which occurred in 76%(!) of this cohort, less even than in the standard care arm where it was 66%. Yet the hardest thing to wrap one’s mind around is the primary endpoint: “2-year cumulative rate of ipsilateral invasive cancer diagnosis, inclusive of all invasive cancers detected at any time after enrollment.” That means all women who received standard surgery with invasive disease detected on the final path—not something typically viewed as some sort of therapeutic failure and instead as a core reason to excise DCIS in its entirety—were included in this endpoint. What’s more, two years is nothing when it comes to long term meaningful breast events following a DCIS diagnosis. With that in mind, the primary endpoint of detection of ipsilateral invasive cancer within two years was 5.9% in the surgery group versus 4.2% in the active surveillance group. The authors thus conclude active surveillance is non-inferior to standard-of-care surgery +/- radiation. In other words, women are forgoing an outpatient breast excision followed often by 5 days of highly conformal partial breast irradiation in favor of indefinite endocrine therapy and frequent mammography +/- biopsies with uncertain long term outcomes.
TBL: There is much left to learn about active surveillance for low-risk DCIS, including better understanding what, if any, intrinsic quality-of-life advantages are to be achieved with this strategy. | Hwang, JAMA 2024
The Study: So much so that some now suggest low-risk DCIS should receive active surveillance akin to low-risk prostate cancer. The prospective non-inferiority COMET trial randomized 957 women with newly-diagnosed low-risk (read: grade 1-2, ER/PR >10%, HER2-negative) DCIS to standard care (n=473) versus active surveillance (n=484) with mammography q6 months. In the surveillance arm, biopsies were performed for suspicious clinical or radiographic changes and treatment recommended only upon histologic confirmation of invasive disease. This all seems pretty straightforward so far, but wait. The “active monitoring” group could receive endocrine therapy per patient/physician preference, which occurred in 76%(!) of this cohort, less even than in the standard care arm where it was 66%. Yet the hardest thing to wrap one’s mind around is the primary endpoint: “2-year cumulative rate of ipsilateral invasive cancer diagnosis, inclusive of all invasive cancers detected at any time after enrollment.” That means all women who received standard surgery with invasive disease detected on the final path—not something typically viewed as some sort of therapeutic failure and instead as a core reason to excise DCIS in its entirety—were included in this endpoint. What’s more, two years is nothing when it comes to long term meaningful breast events following a DCIS diagnosis. With that in mind, the primary endpoint of detection of ipsilateral invasive cancer within two years was 5.9% in the surgery group versus 4.2% in the active surveillance group. The authors thus conclude active surveillance is non-inferior to standard-of-care surgery +/- radiation. In other words, women are forgoing an outpatient breast excision followed often by 5 days of highly conformal partial breast irradiation in favor of indefinite endocrine therapy and frequent mammography +/- biopsies with uncertain long term outcomes.
TBL: There is much left to learn about active surveillance for low-risk DCIS, including better understanding what, if any, intrinsic quality-of-life advantages are to be achieved with this strategy. | Hwang, JAMA 2024