A keloid is a type of raised scar that occurs from an overgrowth of fibrous tissue after a skin injury. While most scars flatten and fade over time, keloids expand beyond the original wound boundaries and can become large and disfiguring. They can result from any type of skin trauma, including surgical cuts, burns, acne, or even ear piercings. For individuals prone to forming these dense scars, radiation therapy has become a specialized treatment used to manage and prevent their recurrence.
The Combined Treatment Approach
Radiation therapy for keloids is seldom used as a standalone procedure. Instead, it is most effective as an adjuvant therapy, meaning it is used in combination with another treatment. The standard protocol involves the surgical excision of the keloid, followed promptly by a course of radiation therapy. Surgery removes the bulk of the overgrown scar tissue, providing an immediate aesthetic improvement.
The timing of the subsequent radiation is an important factor in the treatment’s success. To be most effective, the first dose of radiation is administered within 24 to 48 hours of the surgical excision. This immediate follow-up is planned because the cellular processes that initiate new scar formation begin quickly after the surgical wound is closed. By starting radiation early, the treatment can disrupt these processes before they can lead to the development of a new keloid.
Mechanism of Radiation on Keloid Tissue
The formation of a keloid is driven by skin cells called fibroblasts. Following a skin injury, fibroblasts are responsible for producing collagen, the protein that gives skin its strength and structure, to heal the wound. In people who are prone to keloids, these fibroblasts proliferate excessively and produce far more collagen than is necessary for normal healing. This overproduction of collagen is what creates the dense, fibrous mass characteristic of a keloid.
Radiation therapy targets these overactive fibroblasts to normalize the healing process. The treatment delivers a controlled, low dose of ionizing radiation directly to the surgical site. This energy disrupts the DNA of the rapidly dividing fibroblasts, which inhibits their ability to multiply and generate excess collagen. It interrupts the cycle that leads to abnormal scar tissue growth.
The most common form of radiation used for this purpose is Superficial Radiation Therapy (SRT), such as electron beam therapy or orthovoltage X-rays. These methods deliver radiation that penetrates only a few millimeters into the skin, concentrating the therapeutic effect on the target tissue while sparing deeper structures. The goal is not to completely eliminate the fibroblasts but to modulate their activity, allowing the wound to heal without forming a new keloid.
Treatment Efficacy and Outcomes
When surgical excision is followed by radiation therapy, the success rates for preventing keloid recurrence are high. Studies report recurrence rates in the range of 10-20%. This contrasts with surgical excision alone, where recurrence rates are between 45% and 100%. The addition of radiation changes the prognosis for patients who have struggled with persistent keloids.
A successful outcome does not mean the absence of any scar. The objective is to replace the raised, often itchy, and painful keloid with a flat, soft, and less conspicuous scar that stays within the boundaries of the original surgical incision. For many patients, achieving a normal-looking scar is a significant improvement in appearance and quality of life. The final appearance of the treated area can continue to improve for months after the procedures are complete.
Treatment effectiveness is influenced by the specific radiation dosage and fractionation schedule used. Higher biological effective doses of radiation have been correlated with lower rates of recurrence. Different radiation modalities, such as electron beam therapy and a more targeted form called brachytherapy, demonstrate high efficacy. Post-excisional brachytherapy, where the radiation source is placed in direct contact with the treatment area, has shown recurrence rates as low as 15% in some studies.
Associated Risks and Side Effects
Radiation therapy for keloids carries potential risks and side effects, categorized as short-term or long-term. The most common short-term effects are localized to the treated skin. Patients may experience redness (erythema), mild swelling, itching, or peeling at the radiation site. These reactions are temporary and resolve within a few weeks to months after the treatment course is finished.
Another frequent side effect involves changes in skin pigmentation. The treated area may become darker (hyperpigmentation) or lighter (hypopigmentation) than the surrounding skin. These pigmentary changes are reported in around 30% of cases and can sometimes be long-lasting or permanent, which may be a cosmetic concern, particularly for those with darker skin tones.
The primary long-term concern is the potential risk of inducing a secondary cancer in the treated area years or decades later. However, the radiation used for treating keloids is superficial and delivered at a very low dose, which is much lower than the doses used for treating cancer. Modern studies show that the actual risk is extremely low. While the risk is not zero, the medical consensus is that for appropriate candidates, the benefit of preventing a disfiguring keloid outweighs this small statistical risk.
Patient Candidacy and Considerations
Determining who is a suitable candidate for radiation therapy involves evaluating several factors. The treatment is reserved for patients with a history of recurrent keloids that have failed to respond to other treatments, such as steroid injections, silicone sheeting, or cryotherapy. It is also an option for keloids that are large, located in high-tension areas of the body, or cause significant symptoms like pain and itching.
The location of the keloid is an important factor; for instance, treating a keloid directly over a sensitive organ like the thyroid gland requires meticulous planning to shield the gland from radiation exposure. A patient’s age is also considered, with physicians being more cautious about using radiation on children or very young adults.
A patient’s medical history, including any prior radiation exposure, is reviewed as part of the consultation process. The decision to proceed is a collaborative one, made between the patient, a dermatologist or plastic surgeon, and a radiation oncologist. This allows the patient to make an informed choice that aligns with their health and personal goals.