Is a single day patient friendly methyl aminolevulinate photodynamic therapy illumination scheme for superficial basal cell carcinoma feasible? A randomized multicenter pilot trial

Photodynamic Therapy for the Treatment of Basal Cell Carcinoma: A Comprehensive Review of Randomized Controlled Trials

INTRODUCTION

Basal cell carcinoma (BCC) is the most common skin cancer worldwide and has been reported to have a rising incidence in the last years. Multiple therapeutic modalities are approved for the treatment of BCC, making it difficult for physicians to choose the most suitable option for every patient. Photodynamic therapy (PDT) using either 5-aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) as photosensitizing agents is an established treatment option for low-risk BCC.

OBJECTIVES

This review aims to summarize the available evidence from randomized clinical trials (RCTs) that utilize either ALA or MAL PDT and compare it with other treatment modalities. The main outcomes related to the effectiveness, adverse events, cosmetic outcomes and pain sensation, along with data from long-term follow-ups will be presented and discussed.

METHODS

Thorough literature searches were conducted through the electronic databases ClinicalTrials. gov and Pubmed/MEDLINE from inception up to 28 March 2023. Only studies in English were included. All relevant data were extracted accordingly from the eligible studies.

RESULTS

Eight RCTs included superficial BCC (sBCC) alone, 7 included nodular BCC (nBCC), 2 included both sBCC and nBCC and 1 included BCC of unspecified subtype. Follow-up duration ranged from 3 months to 5 years. Both ALA-PDT and MAL-PDT demonstrated acceptable efficacy, adverse events, cosmetic outcomes and pain sensation while no major differences were observed between them. PDT was less effective than surgery but with better reported cosmetic outcomes.

CONCLUSIONS

PDT is a safe and efficacious treatment option for sBCC and to a lesser extent nBCC.

New, simplified versus standard photodynamic therapy (PDT) regimen for superficial and nodular basal cell carcinoma (BCC): A single-blind, non-inferiority, randomised controlled multicentre study

BACKGROUND

Topical photodynamic therapy (PDT) is an approved and widely used treatment for low-risk basal cell carcinoma (BCC), comprising two sessions with an interval of 1 week. Simplification of the treatment course can be cost-effective, easier to organize, and cause less discomfort for the patients.

METHODS AND FINDINGS

We performed an investigator-initiated, single-blind, non-inferiority, randomized controlled multicentre study with the objective of investigating whether a simpler and more flexible PDT regimen was not >10% less effective than the standard double PDT in the treatment of primary, superficial, and nodular ≤2 mm-thick BCC and evaluate the cosmetic outcome. With a non-inferiority margin of 0.1 and an expected probability complete response of 0.85, 190 tumours were required in each group. Histologically verified BCCs from seven centres in Norway were randomly assigned (1:1) to either receive a new regimen of single PDT with one possible re-treatment of non-complete responding tumours, or the standard regimen. The primary endpoint was the number of tumours with complete response or treatment failure at 36 months of follow-up, assessed by investigators blinded to the treatment regimen. Intention-to-treat and per-protocol analyses were performed. The cosmetic outcome was recorded. The study was registered with ClinicalTrials.gov, NCT-01482104, and EudraCT, 2011-004797-28. A total of 402 BCCs in 246 patients were included; 209 tumours assigned to the new and 193 to the standard regimen. After 36 months, there were 61 treatment failures with the new and 34 failures with the standard regimen. Complete response rate was 69.5% in the new and 81.1% in the standard treatment group. The difference was 11.6% (upper 97.5% CI 20.3), i.e. > than the non-inferiority margin of 10%. Cosmetic outcomes were excellent or good in 92% and 89% following the new and standard regimens, respectively.

CONCLUSIONS

Single PDT with possible re-treatment of primary, superficial, and nodular ≤ 2-mm-thick BCC was significantly less effective than the approved standard double treatment. The cosmetic outcome was favorable and comparable between the two treatment groups.

Enhancing Fractionated Cancer Therapy: A Triple-Anthracene Photosensitizer Unleashes Long-Persistent Photodynamic and Luminous Efficacy

Conventional photodynamic therapy (PDT) is often limited in treating solid tumors due to hypoxic conditions that impede the generation of reactive oxygen species (ROS), which are critical for therapeutic efficacy. To address this issue, a fractionated PDT protocol has been suggested, wherein light irradiation is administered in stages separated by dark intervals to permit oxygen recovery during these breaks. However, the current photosensitizers used in fractionated PDT are incapable of sustaining ROS production during the dark intervals, leading to suboptimal therapeutic outcomes (Table S1). To circumvent this drawback, we have synthesized a novel photosensitizer based on a triple-anthracene derivative that is designed for prolonged ROS generation, even after the cessation of light exposure. Our study reveals a unique photodynamic action of these derivatives, facilitating the direct and effective disruption of biomolecules and significantly improving the efficacy of fractionated PDT (Table S2). Moreover, the existing photosensitizers lack imaging capabilities for monitoring, which constraints the fine-tuning of irradiation parameters (Table S1). Our triple-anthracene derivative also serves as an afterglow imaging agent, emitting sustained luminescence postirradiation. This imaging function allows for the precise optimization of intervals between PDT sessions and aids in determining the timing for subsequent irradiation, thus enabling meticulous control over therapy parameters. Utilizing our novel triple-anthracene photosensitizer, we have formulated a fractionated PDT regimen that effectively eliminates orthotopic pancreatic tumors. This investigation highlights the promise of employing long-persistent photodynamic activity in advanced fractionated PDT approaches to overcome the current limitations of PDT in solid tumor treatment.

Photodynamic Therapy in Treating a Subset of Basal Cell Carcinoma: Strengths, Shortcomings, Comparisons with Surgical Modalities, and Potential Role as Adjunctive Therapy

Basal cell carcinoma (BCC) is the most common skin cancer, for which there are multiple treatment options, including the gold standard Mohs micrographic surgery (MMS), surgical excision, electrodesiccation and curettage, radiation therapy, cryosurgery, and photodynamic therapy (PDT). While PDT is currently approved for treating actinic keratosis, it has been used off-label to treat BCC patients who may not tolerate surgery or other treatment modalities. We present a review of the efficacy of these modalities and describe important considerations that affect the usage of PDT and MMS. ALA-PDT and MAL-PDT are both efficacious treatment options for lower-risk BCC that can serve as non-invasive alternatives to surgical excision with favorable cosmetic outcomes in patients unsuitable to undergo surgery. In particular, PDT may be considered an adjuvant for the prevention and treatment of BCC lesions in patients with some genetic syndromes such as Gorlin syndrome, and in combination with surgical excision in lesions presenting in certain locations. Limitations to PDT include lack of margin control to prevent recurrence, pain, and cost of certain photosensitizers. Future studies should investigate the role of PDT as adjunctive therapy, standardization of protocols, and causes and ways to address recurrence following PDT treatment.

Photodynamic Therapy for Basal Cell Carcinoma: The Clinical Context for Future Research Priorities

Photodynamic therapy (PDT) is an established treatment option for low-risk basal cell carcinoma (BCC). BCC is the most common human cancer and also a convenient cancer in which to study PDT treatment. This review clarifies challenges to researchers evident from the clinical use of PDT in BCC treatment. It outlines the context of PDT and how PDT treatments for BCC have been developed hitherto. The sections examine the development of systemic and subsequently topical photosensitizers, light delivery regimens, and the use of PDT in different patient populations and subtypes of BCC. The outcomes of topical PDT are discussed in comparison with alternative treatments, and topical PDT applications in combination and adjuvant therapy are considered. The intention is to summarize the clinical relevance and expose areas of research need in the BCC context, ultimately to facilitate improvements in PDT treatment.

Interventions for basal cell carcinoma of the skin

BACKGROUND

Basal cell carcinoma (BCC) is the commonest cancer affecting white-skinned individuals, and worldwide incidence is increasing. Although rarely fatal, BCC is associated with significant morbidity and costs. First-line treatment is usually surgical excision, but alternatives are available. New published studies and the development of non-surgical treatments meant an update of our Cochrane Review (first published in 2003, and previously updated in 2007) was timely.

OBJECTIVES

To assess the effects of interventions for BCC in immunocompetent adults.

SEARCH METHODS

We updated our searches of the following databases to November 2019: Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and LILACS.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions for BCC in immunocompetent adults with histologically-proven, primary BCC. Eligible comparators were placebo, active treatment, other treatments, or no treatment.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Primary outcome measures were recurrence at three years and five years (measured clinically) (we included recurrence data outside of these time points if there was no measurement at three or five years) and participant- and observer-rated good/excellent cosmetic outcome. Secondary outcomes included pain during and after treatment, early treatment failure within six months, and adverse effects (AEs). We used GRADE to assess evidence certainty for each outcome.

MAIN RESULTS

We included 52 RCTs (26 new) involving 6690 participants (median 89) in this update. All studies recruited from secondary care outpatient clinics. More males than females were included. Study duration ranged from six weeks to 10 years (average 13 months). Most studies (48/52) included only low-risk BCC (superficial (sBCC) and nodular (nBCC) histological subtypes). The majority of studies were at low or unclear risk of bias for most domains. Twenty-two studies were industry-funded: commercial sponsors conducted most of the studies assessing imiquimod, and just under half of the photodynamic therapy (PDT) studies. Overall, surgical interventions have the lowest recurrence rates. For high-risk facial BCC (high-risk histological subtype or located in the facial 'H-zone' or both), there may be slightly fewer recurrences with Mohs micrographic surgery (MMS) compared to surgical excision (SE) at three years (1.9% versus 2.9%, respectively) (risk ratio (RR) 0.64, 95% confidence interval (CI) 0.16 to 2.64; 1 study, 331 participants; low-certainty evidence) and at five years (3.2% versus 5.2%, respectively) (RR 0.61, 95% CI 0.18 to 2.04; 1 study, 259 participants; low-certainty evidence). However, the 95% CI also includes the possibility of increased risk of recurrence and no difference between treatments. There may be little to no difference regarding improvement of cosmetic outcomes between MMS and SE, judged by participants and observers 18 months post-operatively (one study; low-certainty evidence); however, no raw data were available for this outcome. When comparing imiquimod and SE for nBCC or sBCC at low-risk sites, imiquimod probably results in more recurrences than SE at three years (16.4% versus 1.6%, respectively) (RR 10.30, 95% CI 3.22 to 32.94; 1 study, 401 participants; moderate-certainty evidence) and five years (17.5% versus 2.3%, respectively) (RR 7.73, 95% CI 2.81 to 21.3; 1 study, 383 participants; moderate-certainty evidence). There may be little to no difference in the number of participant-rated good/excellent cosmetic outcomes (RR 1.00, 95% CI 0.94 to 1.06; 1 study, 326 participants; low-certainty evidence). However, imiquimod may result in greater numbers of good/excellent cosmetic outcomes compared to SE when observer-rated (60.6% versus 35.6%, respectively) (RR 1.70, 95% CI 1.35 to 2.15; 1 study, 344 participants; low-certainty evidence). Both cosmetic outcomes were measured at three years. Based on one study of 347 participants with high- and low-risk primary BCC of the face, radiotherapy may result in more recurrences compared to SE under frozen section margin control at three years (5.2% versus 0%, respectively) (RR 19.11, 95% CI 1.12 to 325.78; low-certainty evidence) and at four years (6.4% versus 0.6%, respectively) (RR 11.06, 95% CI 1.44 to 84.77; low-certainty evidence). Radiotherapy probably results in a smaller number of good participant- (RR 0.76, 95% CI 0.63 to 0.91; 50.3% versus 66.1%, respectively) or observer-rated (RR 0.48, 95% CI 0.37 to 0.62; 28.9% versus 60.3%, respectively) good/excellent cosmetic outcomes compared to SE, when measured at four years, where dyspigmentation and telangiectasia can occur (both moderate-certainty evidence). Methyl-aminolevulinate (MAL)-PDT may result in more recurrences compared to SE at three years (36.4% versus 0%, respectively) (RR 26.47, 95% CI 1.63 to 429.92; 1 study; 68 participants with low-risk nBCC in the head and neck area; low-certainty evidence). There were no useable data for measurement at five years. MAL-PDT probably results in greater numbers of participant- (RR 1.18, 95% CI 1.09 to 1.27; 97.3% versus 82.5%) or observer-rated (RR 1.87, 95% CI 1.54 to 2.26; 87.1% versus 46.6%) good/excellent cosmetic outcomes at one year compared to SE (2 studies, 309 participants with low-risk nBCC and sBCC; moderate-certainty evidence). Based on moderate-certainty evidence (single low-risk sBCC), imiquimod probably results in fewer recurrences at three years compared to MAL-PDT (22.8% versus 51.6%, respectively) (RR 0.44, 95% CI 0.32 to 0.62; 277 participants) and five years (28.6% versus 68.6%, respectively) (RR 0.42, 95% CI 0.31 to 0.57; 228 participants). There is probably little to no difference in numbers of observer-rated good/excellent cosmetic outcomes at one year (RR 0.98, 95% CI 0.84 to 1.16; 370 participants). Participant-rated cosmetic outcomes were not measured for this comparison. AEs with surgical interventions include wound infections, graft necrosis and post-operative bleeding. Local AEs such as itching, weeping, pain and redness occur frequently with non-surgical interventions. Treatment-related AEs resulting in study modification or withdrawal occurred with imiquimod and MAL-PDT.

AUTHORS' CONCLUSIONS

Surgical interventions have the lowest recurrence rates, and there may be slightly fewer recurrences with MMS over SE for high-risk facial primary BCC (low-certainty evidence). Non-surgical treatments, when used for low-risk BCC, are less effective than surgical treatments, but recurrence rates are acceptable and cosmetic outcomes are probably superior. Of the non-surgical treatments, imiquimod has the best evidence to support its efficacy. Overall, evidence certainty was low to moderate. Priorities for future research include core outcome measures and studies with longer-term follow-up.