ESTRO 2024 - Abstract Book

S1416

Clinical - Head & neck

ESTRO 2024

Adding induction chemotherapy (IC) to concomitant chemo-radiotherapy (CCR) is the actual standard of care for locally advanced nasopharyngeal carcinoma (NPC) [1,2]. Taxanes-cisplatin-5fluoro-uracil (TPF) and gemcitabine cisplatin (GP) induction regimens are the most used and both proved through randomized trials that they improve metastatic-free and overall survival [4-6]. To date, survival outcomes of these two regimens have not been compared face to face. This study aimed to evaluate the impact of chemotherapy type and doses on survival outcomes of NPC.

Material/Methods:

We retrospectively reviewed the data of patients with locally advanced non-metastatic stage II-IVA NPC treated between 2017 and July 2022 with IC followed by CCR with intensity-modulated radiotherapy (IMRT) and weekly cisplatin (40 mg/m²). IMRT was delivered with an integrated simultaneous boost of 33 daily fractions at a total dose of 69.96 Gy for high-risk volume, considering response to IC, 60 Gy for intermediate-risk volume and 54 Gy for low risk volume. Total cisplatin cumulative dose was calculated for each patient including both induction and concomitant cisplatin doses. Survival analysis for overall survival (OS), loco-regional free survival (LRFS), metastatic free survival (MFS), and disease-free survival (DFS) was performed according to Kaplan-Meier method. Log-rank test was used to compare chemotherapy-related factors that may influence these different survival parameters.

Results:

We included 154 patients. The mean age was 45 and sex ratio was 2.4. Disease was classified as stage II, III and IVA in respectively 13%, 37% and 50%. Patients received 3 IC courses in 96% of cases. It was TPF IC in 118 cases (76%), GP in 20 cases (13%) and other different protocols in 16 cases (11%). Grade 3-4 IC-related acute toxicity was noted in 31% of cases with TPF versus 21% with GP. One hundred-nine patients (71%) received at least 4 concomitant cisplatin courses. Complete response was observed in 147 cases (95.4%).

After a median follow-up of 54 months [20-95], we noted 19 loco-regional (12%) and 34 distant relapses (22%). Five year-OS, LRFS, MFS and DFS were respectively 77.8%, 83.8%, 76.1% and 66.3%.

In subgroup analysis, the loco-regional relapse rate was 12% in patients receiving TFP IC versus 21% in those receiving GP IC (p=0.10). However, the IC regimen did not significantly affect any of the survival outcomes. Receiving 4 or more cisplatin concomitant courses was associated with a better LRFS (87.3 vs 69.4%; p=0.03) and DFS (70.8 vs 55.6%; p=0.028) but had no significant effect on OS and MFS. The subgroups receiving at least 5 cisplatin concomitant courses did not have better survival outcomes than those receiving less. A total cisplatin cumulative dose of at least 380 mg/m² was associated with better OS (85.5 vs 61%; p=0.001), LRFS (88.6 vs 69.6%; p=0.007), MFS (82.4 vs 62.6%; p=0.002) and DFS (73.8 vs 49.2%; p=0.001).

No grade 3-4 late side effects were reported. The most common toxicity was a dry mouth which was grade 2 in 57 cases (37%) and grade 1 in 71 cases (46.1%).

Conclusion:

GP IC appears to be less toxic but seems associated with more locoregional relapses than TPF. When adding IC to CCR, at least 4 courses of concomitant weekly cisplatin seem to be necessary to ensure better LRFS and DFS, but total cisplatin cumulative dose is a more significant prognostic factor predicting all survival outcomes. The debate