Session Item

Adding induction chemotherapy (IC) to concomitant chemo radiotherapy (CCR) is the new standard of care for locally advanced nasopharyngeal carcinoma (NPC). Taxanes-cisplatin-5 fluoro-uracil (TPF) and gemcitabine-cisplatin (GP) regimens proved through randomized trials that they improve metastatic free and overall survival. To date, response to IC of these two regimens has not been compared. The aim of this single institute study was to evaluate and compare tumour volume response to both regimens.

We retrospectively reviewed the data of patients with locally advanced stage III-IV NPC treated between 2017 and 2021. All patients received three IC courses (TPF or GP) followed by CCR with intensity-modulated radiotherapy (IMRT) and weekly cisplatin (40 mg/m²). Patients who received GP IC were compared to 3 TNM-stage-correlated patients treated with TPF IC. IMRT was delivered with integrated simultaneous boost of 33 daily fractions at a total dose of 69.96 Gy. For each patient, two dosimetric-computed tomography (CT) were made: one before the beginning of IC and the second one week after the completion of IC. We delineated tumour volume (GTV T), lymph node volume (GTV N) and total volume (GTV) on both CTs. We compared volumes responses to each regimen.

Forty patients were included: ten received GP and thirty received TPF IC. Mean age was 47 and sex ratio was 1.9. Thirty-six patients (90%) had an UCNT. In the two regimens, half of the patients (50%) were classified as stage III and the other half as stage IV. 

The mean GTV T before IC was 50.4 cm³ [17-221.5]. After IC, there was a decrease in GTV T with an average of 32.3% in GP regimen versus 41% in TPF regimen. The GTV N before IC was 62.9 cm³ on average [3.7-250.7]. The mean regression of its volume was of 48.2% versus 57.1% in GP and TPF regimens respectively. The average total GTV before IC was 113.4 cm³ [28.1-295.9]. The mean decrease in total GTV was 39.5% with GP versus 49.9% with TPF. 

IC allowed reduction of macroscopic tumour and lymph node volumes with both regimens. However, TPF regimen appears to provide a better tumour response than GP. We must validate these results with more patients, longer follow up and correlate this observation with NPCs survival outcomes and toxicity profiles.