Possible Increased Risk of Breast Cancer in FD/MAS Patients

Researchers from Leiden University Medical Center (LUMC) in the Netherlands and the National Institutes of Health (NIH) in the US have recently concluded a study researching the link between breast cancer and fibrous dysplasia and McCune-Albright syndrome (FD/MAS). Their findings suggest that FD/MAS patients may be more likely to develop breast cancer, and at a younger age, than the general population.

“We found that FD patients are about 3 times more likely to develop breast cancer than the general population.” said the lead researcher of the study, Natasha Appelman-Dijkstra, MD, PhD. “We also found that FD patients tended to develop breast cancer at a younger age. The general population is diagnosed at the median age of 62 in the US and 61 in the Netherlands, whereas FD patients were diagnosed at a median age of 36 in the US cohort and 46 in the Dutch cohort.”

The study analyzed the medical histories of 255 female patients, 15 of whom ultimately developed breast cancer. All of the FD/MAS patients diagnosed with breast cancer had polyostotic FD, or MAS with polyostotic FD. None with monostotic FD developed breast cancer.

Of the 15 patients who developed breast cancer, 13 had FD in the thoracic region (ribs, sternum, thoracic vertebrae). The researchers estimate that patients with FD lesions in the thoracic region are somewhere between 6 to 13 times more likely to get breast cancer than the general population. History of precocious puberty or growth hormone excess might also be an additional risk factor.

Thankfully, while FD/MAS patients may be at higher risk for breast cancer, the study also suggests that FD-related breast cancer is likely less aggressive.

Of the 15 patients diagnosed with breast cancer, 10 had ductal carcinoma in situ, which is considered a non-invasive, early-stage breast cancer. Only 5 of the 15 had invasive adenocarcinoma. The prognosis for the FD/MAS patients with breast cancer appears to be very good. Up to 15 years after diagnosis, all of the breast cancer patients were alive and none experienced recurrence (return of cancer) or distant metastases (spread of cancer).

These findings may change the way patients and clinicians approach their care and treatment. “In the Netherlands we will start screening FD/MAS patients for breast cancer at age 40, which is ten years earlier than the general population.” said Dr. Appelman-Dijkstra. “Screening programs should be individually tailored with the treating physician.” said Dr. Appelman-Dijkstra. “Our plan is to screen all Dutch patients with polyostotic FD/MAS or FD in their thoracic region.”

The US researchers also think that the study’s findings should impact screening guidelines. NIH clinicians suggest patients with a history of precocious puberty and growth hormone excess take extra precaution, as these may be drivers of the increased risk. “We recommend women with FD/MAS begin regular screening mammography starting at age 40 years, which is 5 years earlier than the general population.” said Dr. Alison Boyce of the NIH, “However, we think these recommendations apply only to women with polyostotic FD, thoracic FD, and a history of precocious puberty, or growth hormone excess.”

While the researchers recommend earlier screening for FD/MAS patients, they also want patients to understand that the connection between FD/MAS and breast cancer is still uncertain. “Breast cancer is a common disease, which means we would expect some people with FD/MAS to develop breast cancer, even if the two diseases were entirely unrelated. To firmly establish a connection between FD/MAS and breast cancer we need to conduct more studies with larger numbers of patients,” said Dr. Michael Collins of the NIH. There is still much more to learn about a possible link between FD/MAS and cancer. LUMC and NIH researchers, together with the international consortium of FD/MAS investigators are determined to pursue continued funding in support of future research.

These important findings would not have come to light without charitable donations to support FD research.

My PhD student and I noticed that lots of the FD/MAS patients in our database had breast cancer, and that triggered our interest in studying this link,” said Dr. Appelman-Dijkstra. The PhD student who noticed the link, Bas Majoor, is supported by a grant from the Bontius Foundation in Leiden for research into fibrous dysplasia. Dutch FD/MAS patients have been instrumental in Bontius Foundation fundraising efforts.

Researchers at the NIH had made similar observations on the possible association between FD/MAS and breast cancer based on earlier NIH reports and case studies. “By collaborating, we could validate our findings through studying a larger patient cohort beyond national borders,” explained Appleman-Dijkstra.  Both the Dutch and American researchers have been active in the International Consortium on FD which has hosted meetings regularly. Recent scientific meetings in Lyon and a Fibrous Dysplasia Foundation-supported gathering at last year’s ASBMR annual meeting have supported their international collaboration. During these interactions, LUMC and NIH researchers decided to team up to study the link between FD/MAS and breast cancer with more patient data.

The FDF is grateful to Drs. Natasha Appelman-Dijkstra, Neveen Hamdy, Alison Boyce, and Michael Collins, who shared their time and expertise with the Fibrous Dysplasia Foundation so we could share this news with the FD/MAS patient community as soon as possible.

In Summary
All women are at risk for breast cancer. Women with FD/MAS–especially those with a history of precocious puberty  and/or thoracic FD–may be at an increased risk of developing breast cancer at an early age. Fortunately, when breast cancer occurs in women with FD/MAS it appears to be less aggressive. Women with FD/MAS should make sure their doctors are aware of the association between breast cancer and FD/MAS, and consider starting screening at an earlier age.  

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