Abstract 32P
Background
Recent shift in management of breast cancer towards less extensive axillary surgery & increasing use of neoadjuvant therapy presents challenges to determine extent of axillary surgery necessary post neoadjuvant chemotherapy (NAC). NAC results in eradication of axillary lymph node (ALN) metastasis in 40% patients 18F FDG PETCT is more sensitive than conventional staging to identify regional nodal metastases. However, utility of PETCT post NAC has not been studied extensively, especially in Indian subcontinent with unique challenges of inaccessibility, unaffordability & high out of pocket expenditure for cancer treatment Dual tracer sentinel lymph node biopsy & ultrasound guided marker targeted biopsy are not feasible in most Indian hospitals. Thus, a need to tailor recommendations to reduce morbidity without compromising oncologic outcomes In our study we correlated PETCT with post surgery histopathology to understand how accurately PETCT could predict axillary status post NAC.
Methods
Retrospective analysis of 84 locally advanced breast cancer (LABC) with ALN metastasis who underwent NAC followed by ALN dissection from May 2022 to May 2024 18F FDG PETCT post NAC was correlated with final histopathology for ALN positivity. Sensitivity, specificity, positive & negative predictive values of post NAC PETCT was calculated. P value was calculated with McNemar's test.
Results
Sensitivity of post NAC PETCT 81.8% & specificity 98%. Positive predictive value 96% & negative predictive value 89%. Two-tailed P value 0.1306 was not statistically significant. Chi squared 2.286 with 1 degrees of freedom False negative cases by PETCT had subcentimetric ALN at presentation with low mean FDG uptake SUVmax 1.5 & no uptake post NAC. Molecular subtype subset analysis showed lowest sensitivity 66% & negative predictive value 60% in luminal A with 100% sensitivity, specificity, positive & negative predictive values in Her2 enriched & triple negative subtypes.
Conclusions
No significant difference found between PETCT and histopathology indicates reliability of PETCT to determine axillary status post NAC in LABC. Considering retrospective nature and small sample size, further prospective studies should be performed to establish PETCT as a good alternative to axillary surgical staging post NAC in LABC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.