CEACAM5 and invasive lobular breast carcinoma: Elevated CA 15–3 and CEA demonstrated high specificity (as noted above) and moderate-to-strong positive likelihood ratios (CA 15-3: LR + 7.38; CEA: LR + 4.43), suggesting that patients above these thresholds, particularly those with invasive lobular carcinoma or undergoing restaging, may benefit from prioritized PET evaluation or improved interpretation of equivocal PET findings.