Younger women with a family history of breast cancer should receive annual screenings to pick up the disease earlier, a charity says.
Breast Cancer Now funded a study which found cancers were detected sooner when 35 to 39-year-olds at risk had annual mammograms.
NHS screening often starts at the age of 40 for women with a family history.
Experts need to balance the benefits of doing more checks against causing any undue worry or over-treatment.
The study's authors said that more analysis was needed on the risks, costs and benefits of extending the screening programme.
But Baroness Delyth Morgan, the charity's chief executive, called for the government's forthcoming review of NHS screening programmes in England to consider the introduction of scans for women aged 35 to 39 with a family history of breast cancer.
The study, carried out by researchers at the University of Manchester, offered scans to 2,899 women in this age group who were deemed to have a moderate or high risk of the disease after being referred by a GP to a family history clinic.
The screening detected 35 invasive breast cancer tumours, most of which were small and identified before they had reached the lymph nodes - a sign that they had not spread around the body.
In a control group, which did not have the screening, far fewer of the cancers were discovered when they were still small and more had spread to the lymphatic system.
Prof Gareth Evans, the lead author of the study, said the trial demonstrates that annual scans are effective in detecting tumours earlier for this younger age group.
He said overdiagnosis - where people are treated for cancers that are unlikely to prove harmful - was "far less likely" to be an issue with this younger age group.
"For women with a family history, removing a non-invasive tumour so early in their lives is likely to be a cancer preventive," Professor Evans said.
The study did not include women who had specific gene mutations which can increase the risk of the disease.
The charity says regular MRI scans - as is currently recommended - remains the best option for those with faulty BRCA or TP53 genes.
Lives cut 'heartbreakingly short'
If annual mammograms for at risk younger women were made widely available across all four of the UK's NHS services, it could affect up to 86,000 women, the researchers said.
Breast cancer is the most common cancer in the UK, with about 55,000 women being diagnosed each year and 11,500 dying from the disease.
Between 5% and 15% of breast cancers are linked to a family history of the illness.
"We've long known that a family history can define a woman's risk, and that breast cancer can be more aggressive in younger women," said Baroness Morgan.
"So if we can intervene earlier for those at higher risk through annual screening, we believe we may be able to stop the disease cutting so many women's lives so heartbreakingly short."
An NHS England spokeswoman said possible changes to the screening programme will be considered in the review.
She said: "Breast cancer survival is at its highest ever and with improved screening a key focus of the NHS long-term plan, even more cancers will be diagnosed earlier."
The Scottish Government said it continues to monitor and consider all available evidence and recommendations.
Who gets breast screening?
- Women are routinely offered screening when they reach the age of 50 - they will get an invite every three years until their 71st birthday
- The NHS is doing a trial of extending routine screening to some women aged 47-73
- If you have an increased risk of breast cancer because you carry certain genes or have close relatives who have had breast cancer, you may be offered yearly checks. Speak with your doctor about the best options for you