Are certain types of cancer more common with methotrexate?

Are certain cancers more common with methotrexate?

Methotrexate suppresses the immune system and interferes with DNA synthesis, two actions that can raise cancer risk. Large cohort studies show the strongest signal for lymphoma, especially non-Hodgkin lymphoma, where incidence roughly doubles in long-term users compared with the general population. Skin cancers, including squamous cell and basal cell carcinoma, also appear more frequently, with some data suggesting a three- to five-fold increase in patients receiving the drug for psoriasis or rheumatoid arthritis.

Why is lymphoma risk highest?

Methotrexate impairs T-cell surveillance and can trigger Epstein-Barr virus reactivation in B cells, a pathway that drives many of the lymphomas seen in treated patients. The risk climbs with cumulative dose and duration, and it declines after the drug is stopped, although full normalization may take years.

What about other malignancies?

Solid tumors such as lung, breast, or colorectal cancer do not show consistent excess rates once smoking, age, and disease severity are controlled for. Some registries report modest increases in melanoma and urinary-tract cancers, but the absolute numbers remain small and findings are inconsistent across studies.

Does the underlying disease matter?

Patients treated for rheumatoid arthritis or psoriasis already carry an elevated cancer baseline; separating drug effect from disease effect is difficult. In juvenile idiopathic arthritis or inflammatory bowel disease the lymphoma signal appears weaker, possibly because doses and treatment durations differ.

When does risk become clinically relevant?

Most guidelines recommend routine skin checks and age-appropriate cancer screening rather than drug-specific surveillance. Discontinuation is considered if lymphoma is diagnosed, and many cases regress after methotrexate withdrawal alone.

How do alternatives compare?

TNF inhibitors and JAK inhibitors carry their own lymphoma warnings, while hydroxychloroquine and sulfasalazine show little added cancer risk in observational data. Choice of therapy therefore balances disease control against each agent’s safety profile.

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