(Source: eMedicine) Cryotherapy, also known as cryosurgery,
is a commonly used in-office procedure for the treatment
of a variety of benign and malignant lesions. In a recent
report, cryotherapy was the second most common in-office
procedure after skin excision. The mechanism of destruction
is necrosis, which results from the freezing and thawing
of cells. Treated areas reepithelialize. Adverse effects
are usually minor and short-lived.
Dermatologists have used cryotherapy since the turn
of the century. After the development of the vacuum
flask to store subzero liquid elements, such as nitrogen,
oxygen, and hydrogen, the use of cryotherapy dramatically
increased. By the 1940s, liquid nitrogen became more
readily available, and the most common method of application
was by means of a cotton applicator. In 1961, Cooper
introduced a closed-system apparatus to spray liquid
nitrogen. In the late 1960s, metal probes became available.
By 1990, 87% of dermatologists used cryotherapy in their
practice. The general advantages of cryotherapy are
its ease of use, its low cost, and its good cosmetic
results. Most skin cancers are treated with excision
or other destructive procedures, such as electrodesiccation
and curettage. Superficial basal cell skin cancers and
Bowen disease can be treated with cryotherapy.
Recurrence rates for primary basal cell carcinoma vary
with treatment modality. The 5-year recurrence rate
for cryotherapy may be as low as 7.5% if lesions are
chosen judiciously. This percentage compares favorably
with published recurrence rates following other procedures.
Published rates include surgical excision, 10.1%; curettage
and electrodesiccation, 7.7%; radiation therapy, 8.7%;
and all non-Mohs modalities, 8.7%. Because these percentages
are derived from various studies, rather than one randomized
controlled study comparing the different modalities,
they should be viewed as rough approximations. Well-circumscribed
tumors are most suitable for cryotherapy. The indolent
local growth of these well-circumscribed tumors accounts
for the high cure rates quoted in the literature.