Treating a common immune system cancer as a chronic disease can halve the risk of relapse over two years, a study has shown.
Researchers tested a £600-per-month "maintenance therapy" for patients with follicular lymphoma (FL).
The approach involved ongoing treatment with low doses of the targeted antibody drug rituximab.
After two years, 82% of patients who received the two-monthly maintenance therapy were still symptom-free. Their likelihood of relapsing was half that of patients not given ongoing treatment.
Around 1,200 patients took part in the French-led Prima trial, the largest ever to investigate FL.
All started off being treated with rituximab plus standard chemotherapy.
More than 15,000 people are affected by FL in the UK.
European regulators have now approved use of the drug, marketed as MabThera, as a maintenance treatment for FL. However, it is not yet known if the approach will be adopted by the NHS.
First it has to be assessed by the National Institute for Health and Clinical Excellence (NICE) which judges the effectiveness of new treatments in England and Wales. A decision is expected next year.
A key consideration will be cost. Maintenance therapy with rituximab works out at £611 per month, or £7,332 a year.
Professor Graham Jackson, Consultant Haematologist at the Freeman Hospital, Newcastle, said: "The approval of rituximab as firstline maintenance therapy is not only a significant improvement in the way we can manage FL, it also moves us another step closer to a turning point in the way in which cancer is treated."