18F‐fluorodeoxyglucose PET‐CT‐guided pelvic chemoradiation therapy using helical tomotherapy for locally advanced carcinoma cervix without para‐aortic nodal disease: Clinical and patient‐reported outcomes from a prospective phase 2 study

Introduction Locally advanced carcinoma cervix (LACC) is a heterogeneous disease with variable combinations of primary tumour extensions with or without nodal involvement. Metabolic information from 18 fluro‐deoxyglucose positron emission tomography combined with contrast‐enhanced computerized tomography (FDG PET‐CT) may potentially augment treatment decision‐making for LACC. This study ascertained FDG‐PET CT influence on chemoradiation therapy (CTRT) decisions in LACC. We report oncologic and patient‐reported outcome measures (PROMs). Methods FDG PET‐CT scans were reviewed independently by two nuclear medicine specialists and two radiation oncologists. Pelvic CTRT plan digressions were documented and therapy was adapted accordingly. Pelvis radiation (50 Gy/25#/5 weeks) using tomotherapy with weekly cisplatin was used in node‐negative disease. Dose‐escalated simultaneous integrated boost (SIB) 60 Gy/25#/5 weeks was delivered to involved pelvic nodes. All received brachytherapy. Post‐treatment PET‐CT scans were at 6 months. Functional assessment of cancer therapy scores were calculated at baseline, treatment completion, 3 months, 1 year and 3 years. Results Between November 2015 and January 2018, 85 patients were screened, and 77 consented. Extrapelvic disease was seen in 12 (16%) patients (9 para‐aortic nodes, 2 distant metastases and 1 synchronous carcinoma breast); 60 patients were included in the final analysis. Decision changes were seen in 10/77 (13%) screened, 8/60 (13%) included and 32 (53.3%) received SIB. Post‐treatment, 27 (45%) had grade 2 GI/GU/GYN toxicity, one (2%) had grade 3 GI and five (8.3%) had grade 3 neutropenia. At median follow‐up of 54.2 months (95% CI 52.8–58.3), 5‐year local failure, pelvic nodal and para‐aortic nodal‐free survival were 86.8% (95% CI 78.0–96.6), 85.2% (95% CI 76.1–95.3) and 85.2% (95% CI 76.2–95.4). Functional assessment of cancer therapy trial outcome index (FACT TOI) improved by 10.43 at 3 months with no further decline. Grade 3 toxicity was noted for abdominal pain in one (1.7%), cystitis in four (6.7%) and lymphoedema in one (1.7%) at 5 years. Conclusion PET‐CT resulted in major decision changes in 13%. PET‐adapted CTRT was associated with acceptable toxicity, encouraging long‐term survival and improvement in PROMS.