Impact of 18FDG PET/CT on Clinical Management, Cost Effectiveness, and Radiation Exposure in Newly Diagnosed Breast Cancer Patients.

Background: For the initial staging of breast cancer (BC), 18FDG PET/CT is recommended by professional guidelines in stage III (except T3N1) and inflammatory BC (T4d) and optional when conventional imaging is equivocal or suspicious. However, growing evidence also supports its role in the staging of intermediate-risk groups (IIA, IIB, T3N1 of IA). This study aimed to compare the impact of 18FDG PET/CT with conventional imaging (CT-chest+abdomen+pelvis and bone scan; CT-CAP+BS) in staging, cost-effectiveness, and radiation exposure in the initial staging of BC.

Material And Method: A retrospective study (April 2020 2024) included 115 biopsy-proven BC patients who had CT-CAP+BS and 18FDG PET/CT for initial staging. Data were analyzed to see the impact of 18FDG PET/CT on change in staging, cost-effectiveness, and radiation exposure compared to CA-CAP+BS.

Results: Out of 115 patients (113 female and 02 male), 110 had unilateral and 5 had bilateral BC (Invasive Ductal Ca. 107; Non-IDC: 08) with non-significant laterality. The overall upstaging rate for regional nodal and/or distant metastases was 36% (24/66; excluded 49 with stage IV). The overall upstaging rate due to unsuspected higher nodal metastases was 20% (predominantly stage IIA, and IIB). Upstaging rate to stage IV was seen in 17% (11/66; predominantly in IIIA-C). The overall concordance (no change in staging) was seen in 64% (42/66) while no downstaging was found in any patient. In patients with stage-IV disease (n = 49), 18FDG PET/CT identified a higher number of hypermetabolic lesions in 18 (37%), lesser in 07 (14%), and similar in 24 (49%) cases. The estimated cost in Pak rupees for CT-CAP+BS and PET/CT was 139000 and 106000 respectively. The mean effective dose imparted by 18FDG PET/CT was 8.85 mSv compared to the reported 26.6 mSv by CT-CAP+BS.

Conclusion: We conclude that in the initial staging of BC, 18FDG PET/CT compared with CT-CAP+BS has a significant impact on decision-making by upstaging the disease in stage II and III and detecting more metastatic lesions in stage-IV disease. Furthermore, 18FDG PET/CT is more cost-effective and imparts significantly lower radiation exposure as compared with CT+CAP+BS. These findings support the inclusion of 18FDG PET/CT in the initial staging of stage II-IV BC.