A total of 100 dermatologists participated; mean age was 40.6 years (SD, 9.79), with a mean of 12.8 (SD, 8.5) years in dermatology practice. Of these, 65% worked in both public and private settings, 25% public only, and 10% private only; most saw between 300 and 700 patients per week (Table 2). AK was a frequent reason for consultation: for 39% of dermatologists, it represented 11–20% of visits; for 30%, 21–30%.

Respondents estimated that nearly 75% of their patients with AK have Olsen grade I or II lesions—39.8% grade I and 34.3% grade II (Table 2)—and 48.6% present multiple lesions/field cancerization. Up to 35.3% of field-cancerization patients receive PDT, and in 59% of those cases the modality is DL-PDT (Fig. 1).

Figure 1.

Percentage of prescribed treatments for patients with field cancerization.

Among respondents, 38.4% had >5 years’ experience using DL-PDT and 35.4% had 3–5 years. Most (72.7%) alternate between in-clinic administration and self-application at home. When prescribing the latter, dermatologists typically prescribe partially self-applied DL-PDT in 49.44% of patients (the dermatologist performs lesion preparation in clinic; in subsequent days the patient applies the photosensitizer and performs daylight exposure) and fully self-applied DL-PDT in 61.11% (patients complete all steps, including lesion preparation).

Among dermatologists who prescribe DL-PDT only at the hospital or their office (27.3%), common concerns include that patients “may not perform the treatment correctly on their own and fail,” or that they “may exceed the intended treatment area and damage healthy skin” (Fig. 2).

Figure 2.

Reasons for not prescribing self-applied DL-PDT.

Currently, 61.1% of dermatologists who do prescribe at-home DL-PDT do not have a clinic-specific protocol for self-application; they only have a hospital-based DL-PDT protocol.

In 69.4% of cases, the same dermatologist who prescribes and follows the treatment is responsible for instructing patients on self-application; 27.8% report that nursing staff provides these instructions.

A total of 83.3% give patients written materials to review outside the clinic (100% paper format—leaflet, sheets, etc.). In 36.1% of cases, these materials are complemented by a kit with items needed for treatment, most commonly sunscreen (88.5%) and sandpaper/emery files (53.8%).

Dermatologists who prescribe self-applied DL-PDT showed high agreement (83.3%) that “it is essential to involve family/caregivers in at-home treatment,” and that “patients treated with self-applied DL-PDT are satisfied/very satisfied with the results” (79.2%). Agreement levels regarding DL-PDT are shown in Table 3.

Although most dermatology services lack specific protocols for self-applied DL-PDT, there is broad agreement on the key operational factors that determine treatment success at home (Fig. 3). The 4 most relevant ones were (1) appropriately selecting eligible patients for self-applied DL-PDT (98.6%); (2) providing clear instructions (97.2%); and (3) weather conditions (sunny vs cloudy/rainy, ambient temperature, etc.) and (4) total daylight exposure time (both at 62.5%).

Figure 3.

Operational factors in self-applied DL-PDT that most condition treatment success.

Although in Spain the irradiance threshold for DL-PDT (≈130W/m2) is readily met year-round,13 50% of dermatologists who prescribe self-applied DL-PDT prefer the months with higher solar intensity (April–October), though they also prescribe it during November–March.

Regarding time of day, 70.8% recommend performing treatment in the morning from 10:00, 19.4% at any time of day, and 9.8% around midday.

The DL-PDT consensus recommends applying a broad-spectrum sunscreen SPF≥30 with organic/chemical filters at least 15min before starting treatment.14

Among prescribers of self-applied DL-PDT, 61.1% advise sunscreen before treatment. Of these, 46% recommend applying it 16–30min before the photosensitizer; 65.1% recommend a chemical/organic sunscreen; while 92.1% recommend post-treatment photoprotection (Fig. 4).

Figure 4.

Photoprotection recommendations with self-applied DL-PDT.

The DL-PDT protocol stipulates preparing the treatment area before applying the photosensitizer by removing scales or crusts. Options include sandpaper/emery, curettes, keratolytic creams with urea or salicylic acid, microneedling, and even laser.14

For self-applied DL-PDT, 79.2% of prescribers perform some form of curettage or lesion preparation in clinic before patients self-apply treatment; nearly half (47.2%) do this 1–3 days beforehand.

Additionally, 76.4% also recommend that patients perform their own lesion preparation (to remove scales/crusts) before self-applying treatment—most frequently with a salicylic acid cream (78.2%).

For hospital-based DL-PDT, a thin layer of photosensitizer is applied over the AKs without occlusion, and the patient should proceed to daylight exposure within the next 30min (not later).14

In line with these recommendations, 80.8% of dermatologists who prescribe self-applied DL-PDT instruct patients to apply the photosensitizer no more than 30min before exposure, and 70.8% specify applying a thin layer.

As a rule, patients should remain outdoors for 2h to allow adequate protoporphyrin IX (PpIX) accumulation and achieve satisfactory PDT.14 DL-PDT is not recommended at temperatures below 10°C (discomfort outdoors and hindered photosensitizer metabolism) or above 35°C (excessive sweating and heat).

Available evidence indicates that the DL-PDT response rate for mild-to-moderate AK is not influenced by weather on the treatment day (sunny, cloudy, or partly cloudy).14 However, 62.5% of prescribers vary daylight exposure recommendations according to weather conditions, and 65.3% usually check the forecast before prescribing self-applied DL-PDT.

On a sunny summer day, 63.9% recommend 2h of exposure and 36.1% recommend less. On a sunny winter day, the proportion recommending 2h rises to 86.1%, and 12.5% would recommend more than 2h; only 1.4%advise less than 2h in that scenario.

On a cloudy day (10–35°C), 79.2% recommend 2h of daylight exposure and 19.4% recommend more than 2h.

The hospital-based DL-PDT consensus recommends assessing treated lesions after 3 months.13 In keeping with this, for self-applied DL-PDT, 76.4% of respondents schedule follow-up one month or more after treatment.

Overall, 62.5% consider that the effectiveness of self-applied DL-PDT can be meaningfully assessed starting 6–8 weeks into therapy.

Among dermatologists who prescribe self-applied DL-PDT, 95.9% report that patients are satisfied or very satisfied with the process per se, tolerability, and outcomes (Fig. 5).

Figure 5.

Patient satisfaction level with self-applied DL-PDT.

Comparing dermatologist satisfaction between hospital-based and self-applied DL-PDT, 47.2% are equally satisfied with both, 37.5% are more satisfied with hospital-based DL-PDT, and 15.3% prefer self-applied DL-PDT. In any case, 97.2% consider that self-applied DL-PDT is a treatment they will expand in their service.

Finally, dermatologists were asked how certain aspects of self-applied DL-PDT should be handled to help draft a protocol. The most frequent responses are summarized in Table 4.