Adoption of proposed cancer screening guidelines could lead to 17 million women aged 40 to 49 live without free annual mammogram coverage. This has been estimated by a new report, warning that an influential medical panel needs to carefully mull over the proposal before going ahead with its approval.

The Affordable Care Act makes it compulsory for many health plans to provide coverage for certain preventive services without any cost. But for this, procedures have to receive A or B grades from US Preventive Services Task Force, an independent group of experts in prevention and evidence-based medicine.

The letter grades - A, B, C and D – are assigned by the task forces based on the strength of evidence, the benefits and the harm of preventive services.

The task force recommended in 2009 that mammograms for women ages 40-49 receive a C grade, which created a major controversy. There are many uncertainties over the issue. To cite an example, the American Cancer Society, the American College of Radiology and the National Comprehensive Cancer Network say that it is vital to have annual mammograms for women 40 and over.

A health law was enacted to require the Department of Health and Human Services not pay heed to the task force’s recommendation and follow the most current screening guidelines. The law was the result of opposition to the task force’s 2009 recommendation from the Obama administration, members of Congress and several medical organizations.

The task force said last month that it is needed to put a C grade on breast-cancer screening for women ages 40 to 49. The approval for the proposal would mean that health plans would no longer be required to provide full coverage for mammograms for women in this age group.

“The science shows that some women in their 40s will benefit from mammography, most will not, while others will be harmed”, said the task force statement.