Stem-Cell Transplant Patients Face Long-Term Cancer Risk

Allison Gandey

December 07, 2006

December 7, 2006 –- A new study reveals that within 10 years of a hematopoietic stem-cell transplant, patients are almost twice as likely as the general population to develop a second, solid cancer. In a paper published online November 27 in Cancer, researchers report that the risk was particularly evident in patients older than 40 years and in those who received stem cells from a female donor. In such cases, the cancer risk nearly quadrupled.


"Clinicians need to be aware that this can happen posttransplant no matter how early or how late," senior author Donna Forrest, MD, from the University of British Columbia, in Vancouver, told Medscape. "There may be a tendency 10 years after a transplant to say, 'Everything is fine, we're out of the woods,' but this is often when secondary cancers occur, and patients need to be followed for an indefinite period of time."

Dr. Forrest said that she and coauthor Genevieve Gallagher, MD, also from the University of British Columbia, were surprised that the cancer risk continued to rise over time. They also didn't expect to see an increased risk in patients who received stem cells from female donors. "That was even more surprising," she said. "And it's interesting because that's something that hasn't been observed before."

Hematopoietic stem-cell transplantation is a therapeutic option for life-threatening diseases such as leukemia or myelodysplastic syndrome. While the process destroys the patient's own unhealthy stem cells in bone marrow and replaces them with a compatible donor's stem cells, it is also associated with a number of serious short-term adverse effects such as mucositis, infections, and liver vascular obstruction, as well as the potential long-term complication of developing of a second, usually solid, cancer.

Malignancies Occurred at a Median of 6.8 Years After Transplantation

The investigators reviewed the case files of 926 consecutive patients who underwent allogeneic transplantation over an 18-year period. A total of 28 patients developed 30 solid malignancies. The risk ratio of developing a second solid malignancy after allografting, compared with the general population, adjusted for age and sex, was 1.85 (95% CI, 1.0 – 3.06; P = .019).

Malignancies occurred at a median of 6.8 years after transplantation, for a 10-year cumulative incidence of 3.1% (95% CI, 2% – 5%; all solid tumors) and 2.3% (95% CI, 1% – 4%; excluding basal cell carcinoma and carcinoma in situ).

The authors point out that the role of pretransplantation chemotherapy and radiotherapy in the development of a second solid malignancy after hematopoietic stem-cell transplantation remains unclear. "Unfortunately, we did not have comprehensive records of pretransplantation chemotherapy; therefore, we could not assess the impact of initial chemotherapy specifically on the risk of developing a second solid tumor after allogeneic transplantation," they note. "However, we did not observe an increased incidence of second malignancies among patients who had received radiotherapy prior to transplantation."

The researchers write, "Since the risk of developing a solid neoplasm post–allogeneic transplantation continues to increase with time, extended follow-up will be needed to more fully assess the incidence and risk factors for their development."

Cancer. Published online November 27, 2006.

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