This nested case-control investigation aimed to evaluate whether exposure to narrow-band TL-01 ultraviolet B (TL-01) phototherapy is associated with an increased risk of subsequent skin cancers. The analysis focused on three outcomes: basal cell carcinoma (BCC), cutaneous melanoma, and cutaneous squamous cell carcinoma (cSCC).
The study used a cohort of 4,815 patients from Finland who had received TL-01 phototherapy as monotherapy. Personal exposure to TL-01 was obtained from hospital records for each patient. The nested case-control design identified incident skin cancer cases among cohort members and matched controls drawn from the same cohort.
Individual TL-01 exposure was derived from hospital treatment records. The report specifies categorical exposure groups (for example, 1–29 sessions and ≥60 sessions) and also treats exposure as a continuous metric expressed in sessions (used to estimate OR per 20 sessions). No additional exposure details (such as dose per session or cumulative joules) were reported in the source abstract.
For each skin cancer case, four matched controls were selected. Conditional logistic regression was applied to estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for associations between TL-01 exposure and skin cancer outcomes. The analysis included both continuous exposure modeling (OR per 20 sessions) and categorical comparisons using the 1–29 sessions group as the reference category.
Among the cohort there were 38 incident cases of basal cell carcinoma. The analysis showed an increased risk of BCC with higher numbers of TL-01 sessions when exposure was modeled continuously: OR per 20 sessions was 1.36 (95% CI 1.08–1.72). In the categorical analysis using 1–29 sessions as the reference, a substantially higher risk was observed in patients who had received ≥60 TL-01 sessions (OR 4.16, 95% CI 1.49–11.6). These results indicate an exposure–response pattern for BCC within the limits of the study design and available data.
The cohort included 13 cases of cutaneous melanoma and 9 cases of cutaneous squamous cell carcinoma. The study found no statistically significant association between TL-01 exposure and risk of cutaneous melanoma or cSCC in the analyses reported in the abstract.
Occupational outdoor work was considered as a potential confounder given its association with ultraviolet exposure in other studies. According to the report, accounting for occupational outdoor work did not change the observed associations between TL-01 exposure and skin cancer risk. No other confounders or sensitivity analyses are described in the provided abstract.
The authors report an association between higher cumulative TL-01 exposure and increased risk of basal cell carcinoma, with no observed associations for melanoma or cSCC. Limitations noted in the abstract include the relatively small numbers of melanoma and cSCC cases and the implication that larger cohorts with longer follow-up are required to confirm findings and better define risk across skin cancer subtypes. The abstract does not provide additional detail on patient demographics, photosensitivity disorders, immunosuppression status, UV exposure outside phototherapy, or dose metrics beyond session counts.
Within this Finnish cohort of 4,815 patients treated with TL-01 monotherapy, greater numbers of TL-01 sessions were associated with an increased risk of basal cell carcinoma, including a notably higher risk among those with ≥60 sessions. No association was detected for cutaneous melanoma or cutaneous squamous cell carcinoma. The authors conclude that further studies with larger populations and extended follow-up are needed to verify these findings and to better assess the long-term safety of repeated TL-01 phototherapy.