How effective is IFN therapy in treating keloids and hypertrophic scars?

Updated: May 29, 2020
  • Author: Brian Berman, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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IFN injected into the suture line of keloid excision sites may be prophylactic for reducing recurrences. Berman and Flores reported statistically significant fewer keloid recurrences in a study of 124 keloid lesions after postoperative IFN alfa-2b injection treatment (5 million U, 1 million U injected per cm of scar) into keloid excision sites (18%) versus excision alone (51.1%) and TAC treatment (58.4%). [11]

Tredget et al showed a significant increase in the rate of scar improvement compared with the control period of time (P = .004) after injecting 9 patients with hypertrophic scars with 1 X 106 units of human recombinant IFN alfa-2b subcutaneously, daily for 7 days, and then 2 X 106 units administered 3 times per week for 24 weeks in total. [12] Scar assessment (P< .05) and scar volume (P< .05) also improved after 3 months of treatment. No recurrences were reported after stopping IFN therapy.

Conejo-Mir et al reported that 66% of keloids (n = 20) did not recur after 3 years of follow-up after treating 30 keloids with ultrapulse carbon dioxide laser ablation followed by sublesional and perilesional injections of 3 million IU of IFN alfa-2b 3 times per week. [13]

In a 2008 prospective study, Lee et al reported decreases in depth (81.6%, P = .005) and volume (86.6%, P = .002) treating 20 keloids with a combination of intralesional TAC and IFN alfa-2b compared with only a nonsignificant improvement (P = .281 and P = .245, respectively) obtained in 20 keloids treated with TAC alone. [14]

Notably, however, several studies have failed to demonstrate the efficacy of IFN alfa-2b for the treatment of keloids and hypertrophic scars, including a case series of 5 patients treated by Wong et al, [15] a case series by al-Khawajah of 22 patients with keloids using lower doses of IFN alfa-2b than in prior studies, [16] and a prospective randomized clinical trial by Davison et al in which 50 patients with keloids received intraoperative intradermal injections of IFN alfa-2b at 10 million U/mL or TAC at 40 mg/mL, both receiving an extra injection 1 week later. [17]

Hypertrophic scar intralesional injections of human recombinant IFN gamma at 200 mcg (6 X 106 U) per injection for 4 weeks have been reported by Pittet et al to be effective for relieving the symptoms in 6 of 7 patients and decreases in redness, swelling, firmness, and lesion area in 7 of 7 patients. [18] At week 16, the reappearance of symptoms was minimal in only 2 of 7 patients and a small increase in the lesion area occurred in 4 of 7 patients, although these lesions remained smaller than the original area.

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