Mammogram guidelines revised - again

The controversy surrounding mammogram guidelines continues to rage in the US after new guidelines were released by two breast imaging specialist groups who have advised that mammograms should begin at 40 for women with an average risk of breast cancer and by 30 for high-risk women.

This contradicts controversial guidelines from a US advisory panel last year – although it is more in line with what South African experts advise.

The joint recommendations from the American College of Radiology and the Society of Breast Imaging take into account the success of annual mammography screening starting at 40, said Dr Carol Lee of Memorial Sloan-Kettering Cancer Centre in New York, whose study appears in the Journal of the American College of Radiology.

"The significant decrease in breast cancer mortality, which amounts to nearly 30% since 1990, is a major medical success and is due largely to earlier detection of breast cancer through mammography screening," Lee said.

The recommendations have been in the works for about two years, but they serve in part as a rebuttal to guidelines issued in November by the US Preventive Services Task Force (USPSTF), which recommended against routine breast mammograms for women in their 40s to spare them some of the worry and expense of extra tests to distinguish between cancer and harmless lumps.

‘Annual mammograms best’

Those recommendations contradicted years of messages about the need for routine breast cancer screening starting at age 40, sparking a rebellion from breast cancer specialists who argued the guidelines would confuse women and result in more deaths from breast cancer.

"Amidst the furore, the ACR and the SBI stand firmly behind their recommendation that screening mammography should be performed annually beginning at age 40 for women at average risk for breast cancer," Lee and colleagues wrote.

The recommendations also cover the use of magnetic resonance imaging or MRI and breast ultrasound in women who are at high risk of breast cancer because they have mutations in the BRCA1 or BRCA2 genes or a family history of breast cancer.

In these women, breast mammograms should begin by age 30, but not before age 25, when the risk of radiation exposure from the mammograms begins to outweigh the benefits of screening.

What the new US guidelines mean

Dr Phil Evans of the University of Texas South-western Medical Centre in Dallas and president of the Society for Breast Imaging, said the guidelines are based on the latest clinical trial data.

"Where the data was not present, we looked at recommendations that reflect expert consensus opinion," he said, and added that they also help fill in some gaps in terms of how to screen high-risk women. In women who have BRCA mutations, the group recommends annual MRI screening, a more sensitive test, in addition to mammograms starting by age 30.

Women who have a greater than 20%  lifetime risk of breast cancer based on family history should also have annual MRI scans starting at 30. For high-risk women who cannot get an MRI, often because of claustrophobia, a breast ultrasound should be used instead, Evans said.

The two groups did not consider the harms associated with routine screening at an earlier age, such as false positive results, which the task force was trying to balance.

"The reason for that is there have been studies that have shown women would rather have their cancer found, even if it means having to have a biopsy. The harms, from most studies we've seen, did not seem to be all that real," Evans said.

The South African situation

Professor Justus Apffelstaedt (Associate Professor: University of Stellenbosch and Head of the Breast Clinic: Tygerberg Hospital) said that “the USPSTF report must be interpreted in the context in which it was issued and is only with limitations applicable to the South African environment”.

He said that before anyone starts panicking, “it needs to be noted that the report confirms that there is a survival benefit from screening women aged 40-49. The issue that the report has, however, is the "harm" that is being done by screening this age group”.

According to Apffelstaedt, ‘harm’ consists of two components: The psychological and physical harm done to women that are called back and suffer the anxiety of having to go for more diagnostic procedures that will include a biopsy in a significant number of patients.

“Furthermore the systemic ‘harm’ being done by the costs incurred in the health system for call-backs and biopsies. These two ‘harms’ are to be interpreted in the context of screening for breast cancer in the USA,” he said.

SA call back figures better than US ones

However he did question what he called an ‘extraordinary’ call back rate of up to 13% of women who have had a screening mammogram in the US. To put it in perspective he said that most screening programmes outside the US have target recall rates of around 5% and in his practice, there is only a call back of 4.3% of women in that age group.

“The biopsy rate in the USA is also much higher than elsewhere and biopsies are more often than elsewhere, open biopsies. In comparison, in the USA, 2.4% of women will have a biopsy; about half of these are open biopsies. In the UK a similar number of patients undergo a biopsy, but only about a quarter of these are open surgical biopsies.

"Again, compared to our practice, in the 40 - 49 year old patients, only 1.7% will undergo a biopsy; about 95% of these are not open surgical biopsies but needle biopsies that involve much less trauma and cost less than a tenth of what an open biopsy costs.

“Therefore, in the USA much more ‘harm’ is caused by screening than what we regard as acceptable. It emphasises the paramount importance of collecting data and publication for each screening centre of quality indicators such as recall and biopsy rates,” he said.

Breast cancer screening in SA is still effective

And if there was any doubt as to how effective properly run breast cancer screening programmes are here, Apffelstaedt pointed out that breast cancer is up to 2.5 times more common in younger predominantly non-white populations (such as South Africa) versus younger predominantly white populations (such as the USA).

“I therefore estimate, that a properly run breast cancer screening programme in 40-49 year old women in South Africa may have a much bigger effect than seen in the ‘developed’ world,” he said.

References: Sapa, Reuters Health, Professor Justus Apffelstaedt (Associate Professor: University of Stellenbosch and Head of the Breast Clinic: Tygerberg Hospital)

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