689 Background: The treatment landscape of metastatic renal cell carcinoma (mRCC) has evolved over recent years with several systemic anti-cancer therapies (SACT) licensed across different lines of treatment. There is ongoing discussion amongst oncology professionals about how best to optimise treatments in terms of sequencing to maximise the potential number of lines or to give the best treatments first. A previous south-west UK audit was completed in 2021 reviewing the drop off rates across 5 UK sites identifying that 69% of patients were able to receive second line therapy and 34% were able to receive third line therapy. Methods: In this study we conducted retrospective analysis of all patients who commenced treatment with SACT for mRCC between 1st January 2018 and 30th June 2021 in 18 centres across the 4 nations of the United Kingdom. All NHS reimbursed treatment options including the COVID interim treatment guideline options were included. Patients who received SACT as part of a clinical trial were also included. Patients who continued on their respective lines of treatment were censored. We also identified patients who had been on a period of active surveillance before staring SACT in this cohort. Results: 1549 patients (71% male: 29% female) were included. IMDC subgroup patients included 21.6% favourable, 52.3% intermediate, 25.1% poor and 1% unavailable. 9.1% of patients had been on active surveillance before starting SACT – defined as a period of longer than 3 months from mRCC diagnosis to starting SACT. Of those patients that started SACT 60.5% of eligible patients had 2nd line therapy, 25.3% had 3rd line, 7.2% received 4th line therapy and only 1% had 5th line therapy. In the 1st line setting 58.9% received single agent VEGF TKI, 24.5% received combination ipilimumab and nivolumab (IO-IO) immunotherapy, 14 % received IO/ VEGF TKI combination and 2.6% received other/trial treatment. The single agent VEGF TKI ratio for 1st line SACT declined year by year with rising IO-IO and IO/VEGF TKI combination ratios seen. In the second- and third-line settings cabozantinib (33.2% 2nd line and 44.4% 3rd line) and nivolumab (32.8% 2nd line and 22.6% 3rd line) were the most common options. Disease progression or death was the most common cause of SACT discontinuation amounting to 57.4%, 62.5% and 79% of SACT cessation in the 1st, 2nd and 3rd lines respectively. Treatment toxicity SACT discontinuation rates were 22.8%, 21.4% and 10.9% for 1st, 2nd and 3rd lines respectively. Conclusions: These results suggest that with more treatment options available, including combination/immunotherapy therapies, more patients are able to receive second- and third-line therapies. That said there remains significant drop off rates mostly driven by disease progression that would support the use of our most effective therapies in the upfront setting.

whilst 72.2% were attributed to other causes, mostly by cardiovascular or respiratory underlying comorbidities. Cough, dermitis or dyspnea were described as mild (G1) acute toxicity in 7 patients. Chronic toxicity was G1 pneumonitis or fibrosis in 11 patients and one patient developed G5 hemoptysis in a local relapse context. Conclusions: Primary lung cancer VMAT based SBRT achieves good local control rates with a tolerable toxicity. Overall survival may be influenced by patient selection.

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