Secondary Cancers After Hematopoietic Cell Transplantation in Severe Aplastic Anemia

Overview

Long-term follow-up of 329 severe aplastic anemia (SAA) patients treated with hematopoietic cell transplantation (HCT) revealed an 11% cumulative incidence of secondary cancers at 26 years, with a 2-fold increased risk compared to the general population. Chronic graft-versus-host disease (GVHD) significantly increased the risk of skin and oropharyngeal cancers, and unexpected excess breast cancers were observed despite non-irradiation conditioning.

Background

Severe aplastic anemia patients undergoing HCT have seen improved survival, but long-term morbidity, especially secondary cancers, remains a concern. Unlike malignant diseases, SAA conditioning regimens typically exclude total body irradiation, which is a known risk factor for secondary malignancies. Previous studies were limited by heterogeneous treatments and small cohorts. This study analyzed a large, homogeneous cohort with consistent conditioning and GVHD prophylaxis over nearly four decades to better understand secondary cancer risks.

Data Highlights

Key Findings

• Secondary cancers appeared late, mostly between 14 and 34 years post-HCT, with continuous increase up to 45 years.
• Chronic GVHD significantly increased risk of skin and oropharyngeal cancers, doubling cumulative incidence at 26 years.
• Despite absence of irradiation in conditioning, breast cancer incidence was significantly elevated, suggesting other contributing factors.
• Immunomodulatory factors such as ATG use, cyclosporine/methotrexate GVHD prophylaxis, and prior immunosuppressive therapy showed trends toward increased cancer risk but lacked statistical significance individually.
• Two cases of donor-derived myelodysplastic syndromes were observed, raising considerations of disease-related and familial predisposition factors.

Clinical Implications

Clinicians should maintain lifelong surveillance for secondary cancers in SAA patients post-HCT, especially those with chronic GVHD. The unexpected increased breast cancer risk despite non-irradiation conditioning suggests current survivorship guidelines may need revision. Awareness of potential donor-derived malignancies and familial predispositions is important in long-term follow-up.

Conclusion

This large, homogeneous cohort study highlights the persistent and late risk of secondary cancers after HCT for SAA, with chronic GVHD as a key risk factor. These findings underscore the necessity for lifelong specialized follow-up and may prompt reconsideration of long-term cancer screening recommendations.

References

1. Phuong Vo et al. 2021 -- Secondary Cancers Following Hematopoietic Cell Transplantation in Aplastic Anemia: The Role of Persistence
2. Previous studies on irradiation and secondary cancers
3. Reports on chronic GVHD and cancer risk
4. Review on donor cell leukemia in aplastic anemia