Patients are demanding less invasive skin cancer treatments with minimal downtime for recuperation. To deliver on their expectations safely, Anthony M. Rossi, MD, offered the best mix of therapy approaches Friday during “What’s Next: Nonsurgical and Adjuvant Treatment for Skin Cancers.”
“Dermatology is paving the way to catch up to what our patients want,” said Dr. Rossi, assistant attending at Memorial Sloan Kettering Cancer Center and New York Presbyterian Hospital. “The caveat is that not every skin cancer is amenable to nonsurgical or adjuvant approaches.”
Skin cancers conducive for nonsurgical approaches may include squamous cell carcinoma in situ, low-risk superficial or nodular basal cell carcinomas, and, in some circumstances, lentigo maligna.
A nonsurgical approach may be considered for certain cosmetically sensitive anatomical areas such as the nose and face. Nonsurgical treatment also addresses field cancerization issues by effectively treating large areas, such as an entire face or scalp, that are affected by actinic damage and superficial carcinomas.
Imiquimod, photodynamic therapy, and intralesional chemotherapy top the list of nonsurgical treatments for low-risk skin cancers. For example, studies have shown that imiquimod for basal cell carcinoma produces a histological or clinical cure rate in the high 60 to low 80 percent range, depending on subtype.
“However, even if these responses occur, that doesn’t necessarily mean imiquimod is working for a specific patient,” Dr. Rossi said. “We must monitor patients closely for signs the tumor might be persisting or recurring. Close clinical follow-up with inspection, dermoscopy, and, in my clinic, reflectance confocal microscopy help detect persistence.”
As for imiquimod treatment of lentigo maligna, Dr. Rossi first determines the full scope of the damaged skin through whole-lesion and scouting biopsies to ensure it is not invasive melanoma. He also uses reflectance confocal microscopy to visualize below the skin to detect potential areas of subclinical melanoma and recurrence after treatment. The treatment regimen involves daily imiquimod application for at least 12 weeks for effective histologic clearance.
Photodynamic therapy (PDT) with amino-levulanic acid and either red or blue light can be a great nonsurgical treatment for squamous cell carcinoma in situ or early superficial/nodular basal cells.
“I really like PDT for many of my patients because it can treat early skin cancers as well as treat a large area of field cancerization,” Dr. Rossi said. “This usually requires two or three consecutive treatments spaced about one month apart. The healing and cosmesis is quite nice. I also tend to start PDT on patients after they have had multiple non-melanoma skin cancers to try to reduce their actinic burden. The goal is to prevent future occurrences, which really resonates with my patients.”
Radiation can serve as either a primary or adjuvant treatment for primary skin cancer, especially for basal and squamous cell skin cancers. Dr. Rossi adheres to specific radiation treatment criteria and fully discusses the benefits and risks of treatment with patients.
Adjuvant radiation reduces the incidence of local recurrence by eradicating residual basal cell carcinoma. The goal is to target the deeper aspect of the tumor that may not have been cleared by surgery alone.
“The limitation of nonsurgical treatment is not visualizing the entire skin cancer and therefore just treating the tip of the iceberg, leaving the cancer roots mostly intact,”
Dr. Rossi said. “Still, it is important to explore these less invasive treatment options. What’s next will be a new wave of nonsurgical treatment options for skin cancer in the future.”
Treatments of choice
Clinicians have several options to surgery for treating high-risk cancers. Following are some of the options being used.
Radiation can be used as a primary or adjuvant treatment for primary skin cancer, especially basal and squamous cell skin cancers. It is best not to use it on patients under age 55 because of risk for skin cancers in the radiated field, or on the hands or legs because of the risk for skin breakdown.
For basal cell carcinoma, a five-times-a-week imiquimod application for about
six to eight weeks can be effective, and most patients will experience a significant skin response, including erythema, crusting, and skin breakdown. It also can be used
to treat lentigo maligna after using reflectance confocal microscopy to detect potential areas of subclinical melanoma.
For squamous cell skin carcinoma, adjuvant radiation is effective in high-risk areas, such as scalp or head and neck. It also is an effective treatment for tumors deeper than 2 centimeters and with high-risk features on histology.
Intralesional methotrexate chemotherapy
Keratoacanthoma forms of squamous cell carcinoma may respond well to intralesional methotrexate chemotherapy. One to three rounds of methotrexate injections into the base and four quadrants of the keratoacanthoma lesion at four-week intervals can shrink the tumor considerably and even clear it entirely without surgery.