Cancer Risk in Transplant Recipients

HPV-Related Cancers

• Anal cancer is strongly associated with human papillomavirus (HPV) infection, which is present in 80-85% of anal cancers, and immune suppression in transplant recipients significantly increases the risk of persistent HPV infection and subsequent malignancy 1, 2
• Solid organ transplant (SOT) recipients have approximately 2-4 fold increased incidence rate of all types of cancer, and a 3-5 fold increased rate of cancer mortality compared to the general population 3, 4
• Among gynecologic and anogenital cancers in transplant recipients, HPV-related cancers show consistently and strongly elevated standardized incidence ratios (SIRs) 4, 5

Specific Cancer Types with Increased Risk

• Vulvar and vaginal cancers show the highest risk elevation in transplant recipients with SIRs ranging from 7.3 to 23.9 6, 7
• Cervical cancer risk is moderately increased in transplant recipients with SIRs ranging from 2.0 to 5.7 across studies 6, 7

Risk Factors and Mechanisms

• Immunosuppressive therapy required to prevent graft rejection increases the risk of HPV persistence and malignant transformation 8, 2

Screening and Prevention

• HPV vaccination is recommended for transplant recipients, particularly before transplantation and immunosuppressive therapy to ensure high immunogenicity 8
• The quadrivalent or nonavalent HPV vaccines are preferred given the high prevalence of anogenital warts in immunosuppressed patients 8
• Closer surveillance for cervical cancers is warranted in transplant recipients due to the increased risk 3, 4

Clinical Implications

• Most early-stage anal cancers are asymptomatic due to their typically slow growth pattern, which can lead to delayed diagnosis 2, 9
• Immunosuppression can accelerate the progression of precancerous lesions to invasive cancer 9

HPV Vaccination in Renal Transplant Recipients

Rationale for HPV Vaccination in Transplant Recipients

• The European surveillance guidelines recommend HPV vaccination for renal transplant recipients aged 9-26 years, which should ideally be administered before transplantation to ensure optimal immunogenicity 10, 11

Timing of Vaccination

• The European surveillance guidelines suggest that if possible, vaccination should be provided before solid organ transplantation to ensure high immunogenicity 10, 11
• Vaccination is not recommended within 6 months post-transplantation due to high levels of immunosuppression 10, 12
• For patients who did not receive the vaccine pre-transplant, HPV vaccination can be administered after transplantation, but should be delayed until at least 6 months post-transplant 10, 11
• Patients undergoing hematopoietic stem cell transplantation should be vaccinated 6–12 months after transplantation, even if vaccinated beforehand 10, 13

Vaccine Type and Dosing

• The American Journal of Transplantation recommends the quadrivalent or nonavalent HPV vaccines for transplant recipients given the high prevalence of anogenital warts in immunosuppressed patients 11, 14
• A 3-dose schedule (at 0, 2, and 6 months) is recommended for immunocompromised individuals aged 9-26 years 14

Special Considerations

• For female transplant recipients aged ≥26 years, HPV vaccination may still be beneficial, particularly those with chronic graft vs host disease following HSCT 10, 13

Common Pitfalls to Avoid

• Delaying vaccination until after transplantation when it could have been administered pre-transplant 10, 15
• Administering live vaccines to immunocompromised transplant recipients is not recommended, but HPV vaccines are safe for transplant recipients 15, 16

HPV Vaccination Guidelines for Transplant Recipients

Rationale for HPV Vaccination

• Kidney transplant recipients have a higher prevalence of genital warts and increased risk of HPV-related anogenital cancers, including cervical, vulvar, vaginal, and anal cancers, according to the European surveillance guidelines 17

Vaccination Recommendations

• The Infectious Diseases Society of America (IDSA) recommends that solid organ transplant candidates aged 11-26 years receive the HPV vaccine series 18, 19
• The American Journal of Transplantation notes that the FDA has licensed HPV vaccine for adults up to age 45, suggesting potential benefit for unvaccinated transplant recipients in this age range 20

Safety Considerations

• Studies have shown that HPV vaccines are safe in solid organ transplant recipients, although immunogenicity may be somewhat lower than in immunocompetent individuals, as reported by the American Journal of Transplantation 20