Keloid is a unique fibrous metabolic disease of the human dermis characterized by uncontrolled proliferation of fibroblasts and excessive production and deposition of collagen and other connective tissue matrix after various degrees of skin injury, causing disfigurement and varying degrees of dysfunction, accompanied by itching and pain, causing physical and psychological pain to the patient. The local recurrence rate of keloid scarring after simple general surgical excision can be as high as 90%. In order to explore the effective treatment of keloid, this paper analyzes the clinical efficacy of 71 cases of keloid after surgical excision treated with linear gas pedal 6MeV electron beam radiation in our department.
Keloid is a soft tissue skin disease only seen in humans, which affects the appearance and function and significantly reduces the quality of life of patients. It is believed that the etiology of keloid may be related to skin tension, endocrine, familial predisposition and immune factors. Keloid scars are caused by the imbalance of collagen synthesis and degradation during the repair process after local skin injury, resulting in the deposition of large amounts of collagen, proteoglycans and glycoproteins in the extracellular matrix and the disruption of collagen arrangement. It is a difficult skin condition to treat and can occur in any population, with a higher incidence in people of color. Keloid scars occur in the anterior chest area, back of the shoulders, ears, and bearded areas of the face, etc. The lesions are mostly dark red and extend from the lesion to the nearby area, shaped like a crab’s foot, with itching or pain. Patients often have a strong desire for treatment.
Treatments for keloids include surgical treatment, radiation therapy, compression therapy, and local injections of corticosteroids. The recurrence rate of surgical excision of keloids alone is as high as 40% to 100%, and recurrences are larger than in the past. The reasons for recurrence are related to incisional tension, patient race, age, location, and genetic factors. Compression therapy is often not effectively implemented due to the location of the scar and the patient’s compliance. Because monotherapy is prone to recurrence and poor therapeutic results, combination therapy is now generally used. Surgery combined with radiation therapy is considered to be one of the most effective treatments to date.
Our principle of surgical treatment is to use the simplest possible procedure without additional incisions and to reduce local trauma. In cases with smaller keloids, the 1 mm scar margin is preserved and the wound is covered with direct pulling sutures. For larger keloids, the central part of the keloid is completely excised, while the middle layer of the keloid is excised from the peripheral part, and the skin and a small amount of keloid tissue (about 2-3 mm thick) are preserved and the wound is closed in layers without tension. Studies have shown a correlation between the growth pattern of the keloid and its stretching tension, suggesting that the tension within the keloid is uneven, with the peripheral stretching tension being greater than the central one, and that the strong subcutaneous pulling tension around the keloid contributes to its formation. Improper selection of the surgical incision with high tension is one of the factors contributing to the formation of keloid. Reducing tension on postoperative sutures, reducing damage to tissue and reducing inflammatory response are important measures to prevent keloid recurrence after surgery. We make an incision parallel to the skin tension line during surgery to excise the keloid within the scar and preserve part of the outer scar tissue to reduce skin irritation to the scar margin and prevent the keloid from infiltrating and growing into the surrounding skin after surgery.
Radiation therapy has been used to treat keloids for over 100 years. Commonly used radiotherapy modalities include x-ray irradiation, external electron beam (beta-ray) irradiation, and radionuclide dressing irradiation. Previous studies have found that electron beam (beta-ray) lines have higher control rates than superficial x-ray irradiation, and that electron lines have better dose distribution in superficial tissues, so there are fewer side effects. Radiotherapy is not recommended for areas sensitive to radiotherapy such as the thyroid, or for keloids with mild symptoms and small size. Pediatric patients should avoid irradiation as much as possible.
Immediate postoperative radiotherapy can effectively prevent scar recurrence, while the effect of combined preoperative and postoperative radiotherapy is not superior to postoperative radiotherapy alone. In our group, all patients were irradiated with electron beam on the same day after surgery, which has a dosimetric advantage compared with X-ray irradiation by avoiding deep normal tissue damage and increasing the skin surface dose.
The mechanism of radiotherapy is that radiation inhibits fibroblast proliferation and collagen synthesis, and fibroblast proliferation usually occurs within a few hours after surgery. Since the dose is small and not lethal, it can still cause fibroblasts to proliferate and heal the wound to prevent keloid formation without affecting wound healing. Our clinical observations show that the recurrence rate of keloids is significantly higher in the chest wall and back of the shoulder than in other areas, which is similar to the results of other studies. This may be related to the higher tension in these areas, but the exact mechanism is not clear. In addition, we also found a lower recurrence rate in patients with longer disease duration and after multiple local steroid injections, but due to the small number of cases, further observation is needed to conclude.
We used high-energy electron beam (β-radiation) postoperative radiotherapy to take advantage of its good effect on superficial skin scar treatment, easy control and uniform distribution of dose from the skin surface to a certain depth, accurate localization of irradiation field, high dose on the skin surface, low dose at depth, and short treatment time, with a total treatment efficiency of 85.9% and only minor complications such as slight pigmentation. In this group of patients, immediate radiation therapy after in-scar excision was used to reduce surgical suture tension, and radiotherapy inhibited fibroblast overproliferation and reduced collagen synthesis, resulting in a low recurrence rate after surgery, providing a better treatment for keloid scars.