Accutane (Isotretinoin) Cancer Risk Signal Review

Does isotretinoin have a cancer warning?

No. The Absorica label's boxed warning is embryo-fetal toxicity, and the drug is contraindicated in pregnancy [1]. Its warnings list covers psychiatric disorders, intracranial hypertension, serious skin reactions, pancreatitis, lipid abnormalities, hearing impairment, hepatotoxicity, inflammatory bowel disease, musculoskeletal and ocular abnormalities, and hypersensitivity [1]. Cancer is not one of those headings. The older Accutane-format label's boxed warning is also about pregnancy, not cancer [2].

The adverse reactions section lists lymphadenopathy, inflammatory bowel disease, low blood counts, and photosensitizing reactions [1]. It does not list cancer. That is a label fact, not proof that no cancer can occur.

What the label says about sun and skin

The Absorica label counseling says to avoid prolonged exposure to UV rays or sunlight, and the Medication Guide says isotretinoin may make skin more sensitive to light [1]. The adverse reactions section lists photosensitizing reactions and increased sunburn susceptibility [1]. That is a photosensitivity warning, not a skin-cancer warning.

What the retinoid cancer trial shows

Retinoids as a class have been described as having tumor-suppressive capacity, and isotretinoin is a retinoid [4][1]. In a 1990 New England Journal of Medicine trial, 103 patients who were disease-free after head-and-neck squamous-cell cancer were randomized to isotretinoin 50 to 100 mg per square meter of body surface area per day or placebo for 12 months [3]. There was no significant difference in recurrence of the original cancer. Isotretinoin reduced second primary tumors: 2 patients (4%) versus 12 (24%) after a median follow-up of 32 months, P=0.005 [3]. This was a high-dose trial in patients with prior cancer, not the acne regimen of 0.5 to 1 mg/kg/day [1][3]. It does not show a cancer risk or a cancer-prevention benefit from acne treatment.

Why an adverse-event report is not a cancer rate

The FDA adverse event dashboard says reports are often duplicate or incomplete, that a report does not establish the drug caused the event, and that the data cannot be used to estimate how often an event occurs [5].

What the label says about bowel symptoms

Under its inflammatory bowel disease warning, the Absorica label says to discontinue for abdominal pain, rectal bleeding, or severe diarrhea [1]. The label's pretreatment tests are a fasting lipid profile and liver function tests [1].

Bottom line

The labels do not carry a cancer warning, and the retinoid cancer trial cited here was done in cancer patients, not acne patients [1][3]. A cancer risk from standard isotretinoin acne treatment is not established by the label or by that trial.