ESTRO 2024 - Abstract Book

S1333

Clinical - Head & neck

ESTRO 2024

Results:

Early trial termination was based on slower accrual following COVID & competitive immunotherapy trials: 69 pts (out of 78 planned) were included at 11 centers in 2016-2022. They were male 81.2%, 62.7 yo, PS1-2 52.3% & w significant comorbidities 81.7% (real world population-alike), HPV 23.2%, lung-only 82.6%, isolated 58.0% oMets. Median baseline global QoL score was 66.7 (Q1-3 50.0-83.3).

The 57 patients w full QoL had similar 1y-OSwoQoLloss in both arms (~ 13 mo), with better physical functioning & cough by SABR-alone.

In ITT principle analysis (N=69) and with a median follow-up of 53.7 months, median OS was not reached, 1y-OS was 63.4 (95%CI 47.6-84.5) w SABR-alone & 61.7 (95%CI 46.2-82.4) w chemo-SABR. Median PFS was better w chemo SABR but biased by the different CT assessment times (earlier w SABR-alone to reflect surveillance practice after completion of treatments). Relapse occurred in 48 patients, (M=58); repeat SABR-alone was performed in 17/58 patients (29.3%). Local failure at SABR-treated oMets occurred in 7 chemo-SABR & 7 SABR-alone patients. The actuarial local control was 81.3% (70.1 94.2) at one year. The only significant prognostic factor was the number of oMets (p 0.01), with Hazard ratio of 3.36 (95%CI 0.94-12.02, p=0.06) for two oMets and 12.17 (95%CI 2.29-64.66, p=0.003) for three synchronous oMets. OMet site and lung-only oMets were not associated with better survival. Of these local failures at SABR-treated sites, 2 were SABR-reirradiated, 1 was operated on, 9 received systemic treatments (3 combined w immunotherapy, 1/immuno) and 5 underwent no other specific treatment (1 other cancer). Rates of all grade treatment-related toxicities were 43/69 (62.3%): 10/34 (29.4%) w SABR-alone & 33/35 (94.3%) w chemo-SABR. Rates of severe G3-4 toxicities were 24/69 (34.8%): 2/34 (5.9%) w SABR-alone & 21/35 (60.0%) w chemo-SABR. Cost minimization is being computed, including costs of unplanned hospitalizations.

Conclusion:

Omission of upfront chemotherapy in HNSCC patients w genuine oMets led to lower severe toxicity rates, similar survival rate (despite addition of SABR to chemo) & QoL deterioration rates. Local failures at SABR-treated oMets by ICR and cost-savings associated with omission of frontline systemic treatments are being analysed. In trials comparing drugs & ablative oMet-directed treatments, PFS may not be the most relevant endpoint and might be substituted for time under treatments and their toxicities. QoL in asymptomatic oMet patients might be affected more by residual toxicities from primary disease treatments than treatments of metastases. Immunotherapy given alone is better tolerated than chemo but will unlikely become a better option than SABR due to its response rates and costs.

Keywords: oligometastases, SABR, efficacy

References: