Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration

by Ana Rosengurtt (ana.rosengurtt@gmail.com)

Skaane P, Bandos AI, Gullien R et al. (2013) Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration. Eur Radiol 23: 2061.

Dear Editor,

Thank you very much for giving me the opportunity to comment a report on such a prestigious journal.

With great interest I have read the article by Skaane et al. published in European Radiology in 2013, titled “Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration”.

I wonder how an ethical committee had approved two mammographies (2D+3D) as a double reading procedure on each woman for the trial that is the source of that report. It is hard to accept such a trial was ever seriously considered by an ethical committee just because it is as much as double the usual radiation dose, applied on each participant.

My concern raises from evidence available on other serious sources as well.

An informed consent is required for a single mammography screening program in most countries. An additional informed consent is required in Queensland (Australia) for a single mammography screening program to every woman with breast implants, just because breast implants will obscure some of the breast tissue, making it more difficult to detect small breast cancers [1].  Thus, the dose of radiation should be more intense. Althought Skaane et al. set that women with breast implants had not been asked to consider participation, every woman without breast implants that had underwent double screening, received double dose of radiation at once as if she had breast implants.

A group at risk are women with BRCA 1/2 mutation, which is associated with an increased risk of breast cancer. Results published in BMJ in 2012 showed that women carrying this mutation are particularly vulnerable to radiation-induced cancer [2].  Women carrying this mutation who were exposed to diagnostic radiation before the age of 30 were twice as likely to develop breast cancer, compared to those who did not have the mutated gene. They also found that the radiation-induced cancer was dose-responsive, meaning the greater the dose, the higher the risk of cancer developing.

Also is known the risk of ischemic heart disease in women after radiotherapy for breast cancer. The chance is greater for women whom undergo the radiotherapy on the left breast than on the right one [3].  So double reading with mammograms are exposing women to this adverse effect.

Interval cancers between single mammography screening are bad enough to think on screenning with double dose just for two simultaneous mammographies. “Both true and missed interval cancers were of higher stage and grade than matched screen-detected breast. …True interval cancers were more likely to have additional adverse prognostic features of estrogen and progesterone receptor negativity and nonductal morphology cancers” [4].  The National Cancer Institute itself is aware of this issue on interval cancers and alerts on it [5].

It is very hard to believe that there was an ethical committee behind the trial Skaane et al. had reported.

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