Ann Arbor, Mich. - Patients who have had radiation therapyfor cancer often find the therapy affects their skin at thetreatment site.
Ann Arbor, Mich. - Patients who have had radiation therapy for cancer often find the therapy affects their skin at the treatment site.
Dermatologists might see a range of conditions, as a result, including hyperpigmentation, blistering, burns, fibrosis and, rarely, nonhealing ulcers, according to Theodore S. Lawrence, M.D., Ph.D., professor and chair of the department of radiation oncology, University of Michigan, Ann Arbor, and immediate past chairman of the board of the American Society for Therapeutic Radiology and Oncology.
'Skin sparing' approach
Dermatologists typically do not get many patients complaining of cutaneous problems after deep radiation because the therapy, called skin sparing, penetrates deeply into the body, according to Dr. Lawrence.
"In pancreatic cancer, for example, the radiation beams go at least a couple of inches into the body before they give out most of their energy," Dr. Lawrence tells Dermatology Times. "That means, for the great majority of patients, the worst that you will see is minimal hyperpigmentation. The area of hyperpigmentation peaks about six months to a year after treatment and gets a little lighter several years later."
Dr. Lawrence recommends that patients avoid sun exposure post-treatment for the rest of their lives, or, if they cannot avoid the sun, they should apply the strongest sunscreen they can find.
The effects of radiation, however, also occur beneath the surface, he says, where a biopsy would show damage to the small vessels.
Superficial radiation's effects
The dermatologist might commonly see patients who have had superficial radiation.
Treating basal cell skin cancers - especially those on areas such as the eyelid, nose, ear and commissure, which may be difficult for a dermatologic surgeon to address with incisional procedures - can result in cutaneous complications.
"With radiation therapy, we have in the range of a 97 percent control rate for all but the largest basal cell cancers in any of these locations," he says. "But, because the cancer is superficial, radiation oncologists cannot use the deep penetrating beam. When we treat superficial tumors, we usually give a full dose of radiation to the skin, which commonly results in severe skin reactions, or burns. These will occur during a course of radiation, or within one month after the radiation is complete."
Radiation oncologists typically treat the ulcers with antibiotic creams. Skin breakdown from electrons to the eyelid, nose, ear or lip corners typically heal within about three to four months and is undetectable by the human eye by six months, he says.
The preventive message to these patients is the same: Avoid sun exposure in the radiated areas.
Dermatologists might get patients who have fibrosis of the underlying skin, possibly the result of radiation treatment for sarcoma.
"We give high-dose radiation to those areas, which often results in skin breakdown and, six months later, there might be hyperpigmentation. In addition, we see thickening, or scarring, of the tissues under the skin and sometimes that scarring can be very severe," Dr. Lawrence says. "This is often the case after we treat the skin cancers of patients who have metastatic breast cancer, and the cancer recurs on the chest wall, where the breast used to be."
A study (Delanian, et al. J Clin Oncol. 2003; 21:2545-2550) looked at treating these patients with a combination of vitamin E and pentoxifylline showed promise. Dr. Lawrence says that although encouraging, additional studies are needed before this approach can be considered standard.
In rare cases, dermatologists might see patients who have developed nonhealing ulcers as a result of radiation. The treating physician's tendency might be to do a lot of debridement, but according to Dr. Lawrence, that can exacerbate the problem.
"If the dermatologist is not experienced in treating this type of wound, he or she should find someone who is. The best approach is typically to do limited tissue removal and conservative care," he says.