Radiation Oncology: A Question-Based Review


Jing Zeng and Michael J. Swartz

image Background

What is a keloid?

A keloid is a benign fibroproliferative growth −resulting from a connective tissue response to a variety of proposed factors such as surgery, burns, trauma, inflammation, foreign body reactions, endocrine −dysfunction, and occasional spontaneous occurrence.

Is there a racial predilection for keloid formation?

YesPeople of African descent are more likely to be predisposed to keloid formation than other ethnic groups. Any skin insult (piercings, lacerations, infected skin lesions, surgery) can cause keloid formation in predisposed individuals. Less commonly, lesions can occur de novo.

Name 3 common locations for keloids.

Keloids most commonly affect areas of increased skin tension, such as the ears, neck, jaw, presternal chest, shoulders, and upper back.

Name 3 Sx commonly associated with keloids.

Keloids can be asymptomatic but often are pruritic, tender to palpation, or occasionally cause pain.

image Workup/Staging

What is the difference between a keloid and a hypertrophic scar?

Hypertrophic scars may initially appear similar to −keloids but do not extend beyond the margins of the scar. Keloids are more infiltrative and can cause a local reaction such as pain and inflammation. Hypertrophic scars are much less likely to recur after resection.

image Treatment/Prognosis

What are the indications for RT in keloid Tx?

The indications for RT in keloid Tx include −demonstrated recurrence after resection, marginal or incomplete resection, an unfavorable location, or a larger lesion.

Within what time frame should RT be given postop after keloid resection?

PORT for keloids should be initiated within 24 hrs after resection.

What is the typical target RT volume for keloid Tx?

The typical target RT volume for keloid Tx is scar + a 1-cm safety margin.

What is the typical RT dose and fractionation for keloids?

The typical RT dose and fractionation for keloids is 3–4 Gy in 3–4 fx. Single doses of 7.5–10 Gy are also effective (Ragoowansi et al., Plast Reconstr Surg 2003). Some series suggest that a dose of at least 9 Gy is required to maximize the benefit from RT (Lo et al., Radiother Oncol 1990Doornbos et al., IJROBP 1990).

What RT modalities can be used in the Tx of keloids?

For RT Tx of keloids, the most common modalities are lower megavoltage electrons, kilovoltage photons, or brachytherapy.

Name 5 Tx options for keloids other than surgery and RT.

Tx options for keloids other than surgery and RT include steroid injections, pressure earrings, silicone gel sheeting, cryosurgery, laser therapy, imiquimod, and injections of fluorouracil or verapamil.

What is the recurrence rate for keloids after PORT?

The recurrence rate for keloids after PORT is typically 10%–35%. This can vary depending on the size, location, extent of excision, etiology, and other factors.

Is there any randomized data comparing surgery + RT against surgery + steroid injection?

Yes. A prospective randomized trial conducted by Sclafani et al. looked at a series of 31 pts, comparing PORT vs. intralesional steroid injection. The recurrence rate after surgery + RT was 12.5%; the recurrence rate after surgery + steroid injection was 33%. (Dermatol Surg 1996)

For unresectable keloids, what is the efficacy of using RT alone?

Malaker et al. looked at 86 keloids in 64 pts treated with RT alone. 97% had significant regression 18 mos after completing radiotherapy. 63% of the pts surveyed were very happy with the outcome of their Tx. (Clin Oncol 2004)

image Toxicity

What are the most common side effects after RT for keloids?

The most common side effects of RT for keloids are hyperpigmentation, pruritis, and erythema.