When someone is diagnosed with ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS), one of the toughest questions is: What happens next? Not all in situ lesions progress to invasive cancer, yet many people feel pressure to treat aggressively for fear of missing something.
A new study from the American Association for Cancer Research suggests a promising—but still tentative—tool: a polygenic risk score (PRS), a number based on hundreds of inherited genetic variants. This approach may someday help personalize risk predictions for future breast events after an in situ diagnosis.
What the study did
The research team pooled data from two U.K. cohorts: ICICLE, which followed people with DCIS, and GLACIER, which followed those with LCIS. Altogether, the study included 2,169 individuals with DCIS and 185 with LCIS, with a median follow-up of about 11 years.
Researchers calculated each participant’s 313-variant breast cancer polygenic risk score (PRS-313) and used statistical models to test whether it predicted future breast disease—either in the same breast (ipsilateral) or the opposite breast (contralateral).
What the study found
Among people with DCIS, a higher PRS was significantly associated with an increased risk of contralateral breast events. Those in the highest PRS quartile had about twice the risk of contralateral disease compared with those in the lowest quartile. However, there was no statistically significant link between the PRS and ipsilateral events after DCIS.
For those with LCIS, the pattern was different: a higher PRS was associated with ipsilateral breast events, with stronger associations observed among participants who also had a family history of breast cancer.
What this means for DCIS patients
- This study offers early evidence that genetics might one day help personalize DCIS care by identifying who is at greater or lower risk of future breast events.
- For now, PRS testing is not part of standard DCIS care, and these findings should not change current treatment or monitoring plans.
- The research reinforces that many DCIS cases never become invasive, and that better tools are being explored to help avoid unnecessary overtreatment.
- In the future, a polygenic risk score could potentially be combined with imaging, pathology, and family history to create a more individualized risk profile.
For example, a woman with a high PRS might choose closer monitoring or more proactive treatment, while someone with a low PRS might feel more confident in choosing a less aggressive approach. - Continued research will show whether PRS testing can improve real-world decision-making, quality of life, and peace of mind for patients choosing between active monitoring and more aggressive options.
- If validated, PRS could help guide conversations about surveillance intensity or risk-reducing strategies, alongside other clinical factors and personal preferences.
Important caveats
- This was a retrospective study; PRS-313 needs external validation before it can be used clinically.
- The LCIS group was small, which limits how precisely those results can be interpreted.
- PRS-313 has mostly been studied for general ER-positive breast cancer risk; its performance may vary across ancestries and clinical settings.
- The outcomes included both in situ and invasive events—not solely invasive breast cancer.
Researchers plan to continue studying
- Whether combining PRS with imaging and molecular markers could create even stronger risk-prediction tools.
- How these scores perform in diverse populations.
- Whether using PRS in real clinical settings can improve decision-making and quality of life.
Bottom line
This study offers an encouraging glimpse into how genetics might someday help personalize risk predictions after DCIS or LCIS. But it’s not ready for use in decision-making just yet.
The findings suggest that genetic information could eventually help reduce overtreatment and empower women with clearer choices. If you’ve been diagnosed with DCIS or another in situ breast lesion, this research offers hope that more personalized answers are on the way. In the future, your care team may be able to use genetic information—alongside imaging and pathology—to tailor recommendations just for you, ensuring treatment is both effective and necessary.
To read the full study, click here.