KEY POINTS
- This retrospective cohort included 207 consecutive patients aged ≥65 years treated with adjuvant radiotherapy for early-stage breast cancer in 2007–2008. Two radiation oncologists independently graded coronary artery calcification (CAC) on non-contrast simulation CT as absent, mild focal, or extensive.
- CAC was absent in 89 patients (43%), mild in 60 (29%), and extensive in 58 (28%). Extensive calcification was substantially more common among patients with a previous history of ischemic heart disease.
- The primary endpoint occurred in 6/58 patients (10.3%) with extensive CAC versus 0/149 (0%) with absent or mild CAC. Extensive CAC was associated with subsequent ischemic heart disease with an OR of 22.8 (p=0.0008), remaining significant after age adjustment (OR 21.9, p=0.002).
- Among 189 patients without pre-existing ischemic heart disease, events occurred in 4/46 (8.7%) with extensive CAC versus 0/143 with lower CAC scores. The association remained significant both unadjusted (OR 17.45, p=0.006) and after age adjustment (OR 18.47, p=0.008).
- In a national survey, 32/88 radiation oncologists responded; only 3/32 (9.4%) reported consistently documenting CAC and one did so occasionally. 25/32 (78.1%) said they would modify practice if a clinically meaningful association with ischemic disease were established.
CLINICAL TAKEAWAY
Breast RT simulation CT may provide an opportunistic way to identify patients with substantial underlying coronary atherosclerosis and prompt cardiovascular risk assessment without additional imaging. The separation between groups is striking, but with only six events, retrospective data, simplified visual scoring, and limited multivariable adjustment, this is not yet a validated screening strategy.