Finnish Study Identifies Increased Cancer Risks in Patients With Neurofibromatosis Type 1


Key Points

  • Patients with neurofibromatosis type 1 are at increased risk of other cancers in addition to nervous system cancers.
  • Neurofibromatosis type 1 was associated with an increased risk of breast cancer, particularly in younger women.

In a Finnish study reported in the Journal of Clinical Oncology, Uusitalo et al found that patients with neurofibromatosis type 1 (NF1) were at increased risk of other cancers in addition to nervous system disease.

The study included data from a population-based series of patients with neurofibromatosis type 1 (n = 1,404, 19,076 person-years) linked to incident cancers reported to the Finnish Cancer Registry and deaths recorded in the national Population Register Centre between 1987 and 2012.

Increased Risks

Standardized incidence ratios (SIRs) for cancers associated with neurofibromatosis type 1 were 37.5 for brain/central nervous system, 43.5 for soft-tissue, and 1,490 for autonomic nervous system cancers; the SIR for malignant peripheral nerve sheath tumor was 2,056 (all P < .001). Increased risk for other cancers was found in both women (SIR = 1.98) and men (SIR = 1.96; both P < .001). Risk of breast cancer was significantly increased (SIR = 3.04, P < .001) and was particularly high in women aged ≤ 40 years (SIR = 11.1). Significantly or numerically greater risks were also observed for gastrointestinal stromal tumor (GIST; SIR = 34.2, P < .001), malignant fibrous histiocytoma (SIR = 51.2, P < .001), pheochromocytoma (cancer of the adrenal medulla; SIR = 74.3, P < .001), rhabdomyosarcoma (SIR = 45.3, P = .001), thyroid cancer (SIR = 2.71, P = .18), and cancer of the pharynx and mouth (SIR = 3.21, P = .11). Five-year overall survival of patients with cancer and neurofibromatosis type 1 excluding nervous tissue cancers was 54.0% vs 67.5% among patients with cancer without neurofibromatosis type 1 (P = .01).

The investigators noted: “[These] results show that breast cancer, GIST, and pheochromocytoma are clearly NF1-related malignancies. We also suggest that malignant fibrous histiocytoma and thyroid carcinoma should be considered NF1-related cancers. In addition, we observed [cases of] cancers of the pharynx and mouth that represented different morphologic types.”

They concluded: “Our results emphasize the general cancer proclivity of patients with NF1. These findings should translate to clinical practices to determine clinical interventions and focused follow-up of patients with NF1.”

The study was supported by the Cancer Society of Finland.

Juha Peltonen, MD, PhD, of the University of Turku, is the corresponding author of the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.