Your doctor can freeze off your warts using liquid nitrogen in a treatment called cryotherapy. You can have this treatment every one to three weeks depending on how quickly the area heals after each treatment and what happens to your warts.
Two RCTs found that cryotherapy worked about as well as treatment with acid. After six weeks of either treatment, about two-thirds of people had gotten rid of their warts.22 Warts came back in about one-third of people two months later, whichever treatment they had.
It isn’t clear whether cryosurgery works better than using an electrical current (electrosurgery) to get rid of the warts.
Cryotherapy can sometimes cause an infection, but this is rare.
It is safe to have cryotherapy if you’re pregnant.
Cryotherapy is a procedure to treat anogenital warts by freezing. It involves application of nitrous oxide or liquid nitrogen (-196°C) to warts. This very low temperature induces dermal and vascular damage and edema, leading to cellular necrosis in both epidermal and dermal layers of the skin.
Discomfort of the procedure is mild, so anesthesia is not needed. However, a mild topical pain reliever may be administered before the procedure. There are several ways to perform cryotherapy. Liquid nitrogen can be poured into a container with a long, pointed device (cryoprobe). It is then sprayed directly onto the wart. Liquid nitrogen can also been applied with a cotton-tipped swab. Either way, freezing of the wart is done for 10-60 seconds, until it is completely covered with ice. A halo of the surrounding tissue is common. The subsequent thaw is followed by cell death. Treated area dries up and falls off in several days or weeks. If necessary, the freezing and thawing cycle can be repeated several times, although trials have not established the optimal number of applications. This depends on the size of the wart and the area being affected.
Cryotherapy causes little scarring after re-epithelialization. The treatment does not have systemic side effects and only affects tissue to which it is directly applied. Color changes may occur, but they are usually short term.
Efficacy and Recurrence
Cryotherapy was applied in a trial to 64 patients, using a fine needle-spray technique (Damstra RJ, 1991). Warts resolved in 83% within 4 weeks and 96% after 6 weeks. The results were significantly better compared with the control group of 70 patients (13% and 45% after 4 weeks and 6 weeks, respectively). Other studies have found clearance rates of 54-88 % and recurrence rates of 21-40 % (Handley JM, 1991; Eron LJ, 1993; Abdullah AN, 1993; Godley MJ, 1987). ). Most warts cleared with fewer than three treatments. It has been suggested that the recurrence occurs often at sites of previous GW, as a result of the reactivation of virus (Ho GY, 1998). Conversely, if the tissue containing the virus is completely destroyed, the risk of recurrence on the same site is much less. Recurrences in other sites may be explained by re-exposure to HPV or from reactivation of a latent virus.
It seems that cryotheraphy is as effective as trichloroacetic acid (TCA) or podophyllin in terms of clearance rates.
Two trials found no significant difference between trichloroacetic acid and cryotherapy in wart clearance after 6 or 10 weeks of treatment (Abdullah AN, 1993; Godley MJ, 1987). The success rates at 6 weeks were: 21/33 (64%) with trichloroacetic acid v 37/53 (70%) with cryotherapy, RR 0.91, 95% CI 0.67 to 1.25. At 10 weeks the rates were: 43/49 (88%) with trichloroacetic acid v 46/57 (81%) with cryotherapy, RR 1.08, 95% CI 0.92 to 1.24). One of the studies found no significant difference in recurrence at 2 months after the end of 10 weeks of treatment (36% with trichloroacetic acid v 39% with cryotherapy; RR 0.91, 95% CI 0.51 to 1.61) (Godley MJ, 1997).
A randomised, double-blind, multicentre controlled trial (Gilson RJ, 2009) has found that initial combination of 0.15 % cream podophyllotoxin and cryotherapy may be more beneficial in some patients, compared with cryotherapy alone, although overall the clearance rates were similar in both groups. By intention-to-treat analysis, clearances at 4 and 12 weeks were higher in the combination group than with cryotherapy alone, although not statistically significant (RR 1.31, 95% CI 0.95 to 1.81). By week 24 there was no difference between the groups (68.6% and 64.3%, respectively; RR 1.07, CI 0.84 to 1.35). Wart clearance was significantly higher in men (p = 0.001) and those with a past history of warts (p = 0.009) at week 4, but these differences were not longer noted at week 12. The group receiving cryotherapy alone was more prone to relapse.
Two trials compared cryotherapy plus interferon (IFN) injection versus cryotherapy alone. Subcutaneous IFN alpha 2a combined with cryotherapy was no more effective than cryotherapy alone in the treatment of GW (Handley JM, 1991). At 8 weeks 60.7% (17/28 patients) of the IFN group and 67.9% (19/28 patients) of the placebo group were clinically wart-free (not statistically significant); at 12 weeks, the differences between the 2 groups were, again, not significant. Similar response rates were not influenced by gender. In patients cleared of warts at 8 weeks, the recurrence rate at three months was 50% (8/16) and 37.5% (6/16) in the IFN and placebo groups respectively (not significant). Systemic side effects were significantly more common in the IFN than in the placebo group, 50% versus 10.7% of patients (p < 0.01). The presence of multiple warts and perianal/anal canal warts were factors of adverse prognostic. Recurrence of GW following cryotherapy seems not to be prevented by systemically administered interferon (Eron LJ, 1993). A number of 49/97 patients with recurrent GW were treated with cryotherapy plus subcutaneously administered interferon alpha-2a. The rest (48 patients) received cryotherapy plus placebo. The recurrences occur in 10 (28%) interferon recipients and 16 (43%) placebo recipients by completion of IFN therapy. At six months follow-up, 25 (69%) interferon and 27 (73%) treated patients experienced recurrences. In a single blind study, 42 male patients with ano-genital warts were randomly allocated to either cryotherapy or electrocautery. Patients undergoing cryotherapy required a mean of 2-6 sessions, while those receiving electrocautery required a mean of 1-4 treatments. There was no significant difference in wart clearance at 3 month follow-up between cryotherapy and electrosurgery (10/18 [56 %] with cryotherapy v 10/24 [42%] with electrosurgery; RR 1.33, 95% CI 0.71 to 2.50). Cryotherapy was qualitatively much more acceptable to the patients, as it did not require injections of local anesthetic. This treatment seems particularly suited to patients with widely scattered warts who are unable to attend for regular treatment. (Simmons PD, 1981). A recent study (Mi X, 2011) has found that cryotherapy plus photodynamic therapy may be more efficient than cryotherpay alone in treating GW. After two treatments, the complete response rates in the combined group were 32.4% (36/111) and 32.6% (43/132) in the cryotherapy group. The recurrence rates in the combined group and cryotherapy group were 24.3% (27/111) and 31.1% (41/132). The adverse effects in each group included mild to moderate pain, edema, erosion and skin discoloration. Cryotherapy for treatment of GW was safely and successfully used in pregnant women. (Bergman A, 1984). Thirty-four pregnant women in the second (4 cases) and third (30 cases) trimesters of pregnancy underwent cryosurgery. No fetal, maternal or neonatal complications occurred during or following treatment. No recurrences were observed before or six weeks following delivery. Cryotherapy eliminated the need for elective cesarean section in many patients with GW. It appears that cryotherapy can be safely used in pregnancy, irrespective of the gestational age. In a 3-month follow up period, cryotherapy was also efficient in children aged 1-11 years of age (Stefanaki C, 2011). Overall, the advantages of cryotherapy include ease of application and rapid destructive effect. It may have special benefit in treating bulky lesions, grouped lesions, and lesions on hair-bearing areas. With no systemic side effects and only minor local ones, cryotherapy is an effective method for treating GW. 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