Lung cancer complete radiographic response with PULSAR

A woman in her early 80s with a history of smoking, limited scleroderma, interstitial lung disease (ILD) and pulmonary arterial hypertension developed a right suprahilar mass, avid on positron emission tomography (PET) scan. A biopsy was not performed due to the high risk of complications and the high positive predictive value of malignancy. She was staged as IA3: cT1c N0 M0 and recommended for empiric treatment with stereotactic ablative body radiotherapy (SABR). To manage the risk of treatment-related toxicity due to ILD and the tumour's central location, an adaptive personalised ultra-fractionated stereotactic adaptive radiotherapy (PULSAR) approach was selected, with treatments administered every 3 weeks. A plan for 4000 cGy in 5 fractions was devised, but with each successive fraction, the tumour shrank significantly, resulting in a complete radiographic response and cessation of treatment after 4 fractions. PULSAR may offer a safer approach for managing high-risk lung cancer patients undergoing SABR, but it also introduces unique challenges, such as the potential for complete radiographic response or progression during treatment.