Utility of [18F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG PET/CT) in the Initial Staging and Response Assessment of Locally Advanced Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

Abstract

In India up to 50 % of breast cancer patients still present as locally advanced breast cancer (LABC). The conventional methods of metastatic work up include physical examination, bone scan, chest & abdominal imaging, and biochemical tests. It is likely that the conventional staging underestimates the extent of initial spread and there is a need for more sophisticated staging procedure. The PET/CT can detect extra-axillary and occult distant metastases and also aid in predicting response to chemotherapy at an early point in time. To evaluate the utility of FDG PET/CT in initial staging and response assessment of patients with LABC receiving NACT. A prospective study of all biopsy confirmed female patients diagnosed with LABC receiving NACT from April 2013 to May 2014. The conventional work up included serum chemistry, CECT chest and abdomen and bone scan. A baseline whole body PET/CT was done in all patients. A repeat staging evaluation and a whole body PET/CT was done after 2/3rd cycle of NACT in non-responders and after 3/4 cycles in clinical responders. The histopathology report of the operative specimen was used to document the pathological response. The FDG PET/CT reported distant metastases in 11 of 38 patients, where as conventional imaging revealed metastases in only 6. Almost all the distant lesions detected by conventional imaging were detected with PET/CT, which showed additional sites of metastasis in 3 patients. In 2 patients, PET/CT detected osteolytic bone metastasis which were not detected by bone scan. In 5 patients PET CT detected N3 disease which were missed on conventional imaging. A total of 14 patients had second PET/CT done to assess the response to NACT and 11 patients underwent surgery. Two patients had complete pathological response. Of these 1 patient had complete metabolic and morphologic response and other had complete metabolic and partial morphologic response on second PET/CT scan. The 18 FDG PET/CT can detect more number of metastasis as well as additional sites of metastasis compared to conventional methods. The response assessment resulted in change of treatment regimen in 14 % of patients.

Baseline Staging Imaging for Distant Metastasis in Women with Stages I, II, and III Breast Cancer

“…Thirty-two studies assessing imaging modalities [anatomic: chest radiography, liver ultrasonography, chestabdomen-pelvis computed tomography (ct); metabolic: integrated positron-emission tomography (pet)/ct, integrated pet/magnetic resonance imaging (mri), bone scintigraphy] for staging in women with newly diagnosed bca and reporting the outcomes of interest were retained: one systematic review 12 , fourteen prospective cohort studies [13][14][15][16][17][18][19][20][21][22][23][24][25][26] , and seventeen retrospective studies [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] . The study population comprised women with all presentations of bca (including locally advanced bca 14,15,17,20,21,26 , inflammatory bca 21 , and invasive lobular and ductal carcinoma 35 ) and a mixed population of newly diagnosed bca. All studies reported data about the overall prevalence of asymptomatic distant metastases and the prevalence of metastases by site and by stage of disease at the time of initial diagnosis.…”

“…The reference standard was considered on the basis of clinical and short-term follow-up imaging of metastatic lesions, or on the judgment of a multidisciplinary tumour board when biopsy or histopathology was not feasible, or both, because no "gold standard" for the detection of real metastases has been established. Fifteen studies did not provide enough information to determine whether the results of the reference standard test were blinded to the results of the index test 15,17,19,20,23,26,[30][31][32]34,[38][39][40][41]43 , and the risk for bias is related to the potential influence of previous knowledge on test interpretation 44 .…”

“…Stage III: For stage iii bca, the prevalence of distant metastases was reported in nineteen studies of pet/ct [13][14][15][17][18][19][20][21][22][25][26][27][28][29]35,36,39,41,43 , four studies of conventional imaging 14,17,38,40 , and one study of both imaging modalities 42 .…”