Spontaneous regression of well-differentiated squamous cell skin cancer following partial, diagnostic biopsy: retrospective cohort in Queensland

Introduction: Well-differentiated squamous cell skin cancer (WDSCC) is common in sun-exposed populations. Guidelines promote active treatment, with excision preferred. Isolated cases of spontaneous regression (SR) have been reported. Having observed multiple patients with apparent SR following partial, diagnostic biopsy, we did a retrospective cohort study to explore this further. Objectives: We sought to report frequency of SR of WDSCC following partial biopsy by a general practitioner (GP) in a primary care setting and referral to a public hospital general surgery service for excision, to report patient characteristics, and to estimate the time interval between biopsy and SR. Methods: Retrospective cohort study (22 months) of patients in Queensland, Australia, with a diagnosis of WDSCC following a partial biopsy by a GP. SR was defined as no clinical or dermoscopy evidence of squamous cell carcinoma (SCC). Results: Among 153 consecutive patients with WDSCC referred for excision, 51 showed SR at consultation (33.3%, 95% CI: 25.6–41). There was no significant difference in age or sex of the SR and non-SR groups. In almost all patients with SR (N=49, 96.1%), lesions were located below the knee, compared with 90 (88.2%, P=0.042) without SR. Average interval between biopsy and surgical consultation was 13.6 weeks (range 2.7–24.7 weeks). Conclusions: WDSCC may spontaneously resolve following partial, diagnostic biopsy more often than previously reported. These preliminary observations may have implications for treatment options, especially among frail patients with comorbidities.