PACTUS: A two-week radiotherapy regimen for patients with anal squamous cell carcinoma unsuitable for standard chemoradiotherapy—a retrospective single-centre experience
Abstract
Introduction Anal squamous cell carcinoma (ASCC) is rare, and optimal treatment for patients unsuitable for definitive chemoradiotherapy remains undefined. This study describes PACTUS (Palliative Anal Cancer Treatment Uppsala Style), a two-week radiotherapy regimen designed for symptom relief and potentially durable local control. Methods We retrospectively reviewed consecutive patients with ASCC treated with palliative-intent radiotherapy at Uppsala University Hospital (2017–2025). The principal cohort received PACTUS (40 Gy in 10 fractions). Patients treated with Short-course or Quad Shot were included as contextual case series. Treatment selection was based on patient fitness, anticipated tolerance, prognosis, logistics, and patient preference. Overall survival (OS) was measured from radiotherapy initiation. Clinical response, symptom outcomes, and adverse effects were summarized using evaluable denominators. Results Of 735 patients treated for ASCC, 35 (4.7%) received palliative-intent radiotherapy: 28 received PACTUS, 4 Short-course, and 3 Quad Shot. The median age was 80 years (range, 60–97), 25 (71%) were women, and 30 (86%) had an ECOG performance status ≥3. Elective nodal irradiation was delivered to 24/28 patients in PACTUS. The median OS in PACTUS cohort was 30 months. At the data cut-off (April 2, 2026), 20 patients had died: 14/28 (50%) in PACTUS, 4/4 (100%) in Short-course, and 2/3 (67%) in Quad Shot. Median follow-up among surviving patients was 20 months (range, 4–71 months). Clinical response was evaluable in 15/35 (43%) patients and symptom outcomes in 13/35 (37%); therefore, these findings were not considered representative of the full cohort. Toxicity was not collected systematically or graded prospectively. Conclusions PACTUS was feasible in this selected cohort of predominantly elderly and comorbid patients and warrants prospective evaluation. However, because treatment selection was guided by patient fitness and anticipated treatment tolerance, comparisons between the alternative regimens are descriptive only and cannot establish comparative effectiveness or a survival benefit.