KEY POINTS
- Among 735 patients with anal squamous cell carcinoma treated at Uppsala from 2017–2025, only 35 received palliative-intent RT: 28 PACTUS, four short-course RT, and three Quad Shot. Median age was 80 years, 86% had ECOG ≥3, and 97% had a Charlson Comorbidity Index ≥5.
- PACTUS was designed as a relatively intensive abbreviated regimen rather than conventional low-dose palliation. Standard treatment delivered 40 Gy in 10 fractions over approximately two weeks using VMAT with an SIB: 4 Gy/fraction to the primary and ≥2-cm nodes, 3.6 Gy to smaller involved nodes, and 3.2 Gy to elective regions.
- Elective nodal irradiation was used in 24/28 patients (86%), reflecting an intent that sometimes extended beyond immediate symptom relief toward durable locoregional control.
- Twenty patients completed the planned ten fractions; seven received 9 × 4.3 Gy because of scheduling around public holidays and one ultimately received 11 fractions following an interruption and partial response.
- Median overall survival after PACTUS was 30 months. The short-course and Quad Shot groups each had a median OS of 4 months, but these comparisons are not interpretable because fitter patients with better prognosis were preferentially selected for PACTUS.
- Response data were highly incomplete. Only 12 PACTUS patients had an evaluable early clinical assessment; 11/12 had a clinical complete response and 1/12 a partial response. Symptom outcomes were available for only 13/35 patients overall, with improvement documented in eight.
- Toxicity was neither prospectively collected nor consistently graded. Two PACTUS patients (7%) required unplanned hospitalization within one week of RT, and one patient developed severe persistent hematuria/cystitis considered potentially radiation-related and later died; therefore, a reliable toxicity rate cannot be estimated.
CLINICAL TAKEAWAY
For very frail patients with anal cancer who cannot tolerate standard chemoradiotherapy, 40 Gy in 10 fractions is an intriguing middle ground between conventional definitive CRT and low-dose palliation. The apparent durability is notable, but extensive missing outcome data and strong selection bias mean PACTUS needs prospective evaluation before its efficacy or safety can be judged.