Heal House Vitiligo Research 32 · Original Article
Does Long-term Phototherapy for Vitiligo Increase the Risk of Skin Cancer?
Evaluation for Skin Cancer and Precancer in Patients With Vitiligo Treated With Long-term Narrowband UV-B Phototherapy.
In short
Even after receiving hundreds of phototherapy sessions, the risk of skin cancer did not increase. However, exceeding 200 sessions may slightly increase the risk of actinic keratosis, a precancerous condition, so it is advisable to monitor the skin.
"If it's a treatment with UV light, won't it cause skin cancer if done for a long time?" Many people ask this when phototherapy is recommended. It is a reasonable concern. However, the safety of long-term phototherapy for vitiligo had not been properly established. So I examined data from over 60,000 vitiligo patients nationwide. I checked whether skin cancer and precancerous lesions actually increased according to the number of phototherapy sessions received.
Q1 Does frequent phototherapy increase the risk of skin cancer?
To state the conclusion first, skin cancer did not increase regardless of how many sessions were received. We compared 60,321 vitiligo patients by dividing them into groups based on the number of phototherapy sessions, from those who never received any to those who received 200 or more sessions. Non-melanoma skin cancer, melanoma, and Bowen's disease all did not show an increased risk compared to those who did not receive treatment. This was true even in the 717 patients who received 500 or more sessions. In the table below, numbers close to 1 mean 'no difference.'
Risk of skin cancer and precancerous lesions in patients with 200 or more phototherapy sessions (compared to untreated group)
| Item | Hazard ratio (HR) | In simple terms |
|---|---|---|
| Non-melanoma skin cancer | 0.905 | No increase |
| Melanoma | 0.539 | No increase |
| Bowen's disease | 1.021 | No increase |
| Actinic keratosis (precancerous) | 2.269 | Approximately 2.3 times (monitoring needed) |
Q2 So were there no problems at all?
There was one point worth noting. In patients who received 200 or more phototherapy sessions, actinic keratosis increased by approximately 2.3 times. Actinic keratosis is a precancerous lesion. It is not cancer, but if left untreated for a long time, it can develop into skin cancer. Once detected, it can be easily treated and monitored. In other words, skin cancer itself did not increase; rather, it can be understood as some signs of long-term UV exposure appearing. This is why patients who receive more treatment sessions should regularly examine their skin.
Q3 Can we consider phototherapy safe?
Yes, we can say that the risk of skin cancer does not increase even with long-term narrowband UVB phototherapy. Vitiligo often requires treatment over many years. These results provide a strong basis to continue that long journey with confidence. However, 'safe' does not mean 'no need to pay any attention.' Patients who receive many treatment sessions should regularly check for changes such as actinic keratosis. After all, there is a big difference between going through treatment knowing it is safe and going through it anxiously, without knowing.
Closing remarks
Every time I recommended phototherapy, I faced the concern about skin cancer. Now I can respond with a solid answer based on data from over 60,000 patients. The most valuable thing is being able to tell vitiligo patients who need to continue treatment over many years that this method is safe based on evidence. Of course, for patients who receive a very large number of treatment sessions, it seems wise to also recommend regular skin checks as a sensible precaution.
