Radiotherapy for Wilms Tumour Increases Breast Cancer Risk

Screening guidelines for female survivors of Wilms tumour may need to be reassessed

medwireNews: Receiving chest radiotherapy for the treatment of pulmonary metastases in patients with Wilms tumour (WT) elevates the risk of developing breast cancer early, research suggests.

Norman Breslow, from the University of Washington in Seattle, USA, and co-workers followed up 2492 female participants in the National Wilms Tumor Studies 1 to 4 (1969-1995) from 15 years of age until the end of June 2013.

A total of 29 incidences of invasive breast cancer were identified in 28 individuals over 31,755 person-years of follow-up, giving a breast cancer incidence that was a significant 9.1 times the rate expected in the general US population. The cumulative risk at age 40 years (CR40) was 4.5%, the researchers report in Cancer.

The increased incidence was seen primarily in participants who had received chest irradiation, for whom the rate was a significant 27.6 times higher than would normally be expected (with a CR40 of 14.8%), whereas for women not receiving radiotherapy, the rate was a nonsignificant 2.2 times higher than expected.

The risk of breast cancer was also amplified in those who received only abdominal radiotherapy, but not significantly so compared with no radiotherapy.

The age at WT diagnosis was a significant risk factor, irrespective of the use of chest radiotherapy. The rate of breast cancer among individuals who were 10 years or older when their WT was diagnosed was 23.6 times that of the general population and these individuals were 4.6 times more likely to develop breast cancer than patients diagnosed at a younger age.

Moreover, patients who received radiation at a dose of 12 Gy or below were as likely to develop breast cancer as those who received a higher dose (14.4 vs 14.2%).

The researchers point out that the current guidelines suggest yearly mammography and breast magnetic resonance imaging starting at age 25 years or 8 years after treatment culmination only for survivors of childhood cancer who received radiotherapy to the chest or mantle at a dose of 20 Gy or above. However, their findings suggest that "irradiation of the entire chest with 12 Gy carried a significant hazard of early [breast cancer]".

Jennifer Dean and Jeffrey Dome, from Children’s National Health System, Washington, DC, USA, comment in an accompanying editorial that compliance with breast cancer surveillance tends to be low among adult survivors of childhood cancer. They add that “barriers such as education of both survivors and [oncology] providers should be addressed and mitigated”.

References

Lange JM, Takashima JR, Peterson SM, et al. Breast cancer in female survivors of Wilms tumor: A report from the National Wilms Tumor late effects study. Cancer; Advance online publication 27 October 2014 doi:10.1002/cncr.28908

Dean JB, Dome JS. Breast cancer in Wilms tumor survivors: New insights into primary and secondary prevention. Cancer; Advance online publication 27 October 2014 doi:10.1002/cncr.28906

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