A pioneering cancer treatment hailed as the future of oncology is significantly less effective for women than for men, new research has revealed, prompting accusations of sexism in drug development.

A major review published in The Lancet found immunotherapy to be, on average, half as beneficial for female cancer sufferers.

The family of drugs stimulates the body’s immune system to destroy cancerous cells while leaving healthy cells intact.

NHS patients with some lung, neck and head cancers already have access to the treatment and it is expected to become available to many more categories of patient over the next few years.

The new analysis - the first of its kind - found consistently better outcomes for men taking the drugs than women, possibly due to immune system and hormonal differences.

However, immunotherapy was still found to be more effective for women than traditional cancer drugs.

The authors found that key drug trials were more likely to have been populated by male than female participants, but that doctors then applied the results equally across the sexes.

It means oncologists have been prescribing immunotherapy to women based on safety and efficacy data gathered predominantly from men.