Population-based survival for cervical cancer in Singapore, 1968-1992

Cost-effectiveness of different human papillomavirus vaccines in Singapore

Background

Human papillomavirus (HPV) vaccines are widely available and there have been studies exploring their potential clinical impact and cost-effectiveness. However, few studies have compared the cost-effectiveness among the 2 main vaccines available - a bivalent vaccine against HPV 16/18, and a quadrivalent vaccine against 6/11/16/18. We explore the cost-effectiveness of these two HPV vaccines in tropical Singapore.

Methods

We developed a Markov state-transition model to represent the natural history of cervical cancer to predict HPV infection, cancer incidence, mortality, and costs. Cytologic screening and treatment of different outcomes of HPV infection were incorporated. Vaccination was provided to a cohort of 12-year old females in Singapore, followed up until death. Based on available vaccines on the market, the bivalent vaccine had increased effectiveness against a wider range of HPV types, while the quadrivalent vaccine had effectiveness against genital warts. Incremental cost-effectiveness ratios (ICER) compared vaccination to no-vaccination, and between the two vaccines. Sensitivity analyses explored differences in vaccine effectiveness and uptake, and other key input parameters.

Results

For the no vaccination scenario, 229 cervical cancer cases occurred over the cohort's lifetime. The total discounted cost per individual due to HPV infection was SGD$275 with 28.54 discounted life-years. With 100% vaccine coverage, the quadrivalent vaccine reduced cancers by 176, and had an ICER of SGD$12,866 per life-year saved. For the bivalent vaccine, 197 cancers were prevented with an ICER of $12,827 per life-year saved. Comparing the bivalent to the quadrivalent vaccine, the ICER was $12,488 per life-year saved. However, the cost per QALY saved for the quadrivalent vaccine compared to no vaccine was $9,071, while it was $10,392 for the bivalent vaccine, with the quadrivalent vaccine dominating the bivalent vaccine due to the additional QALY effect from reduction in genital warts. The overall outcomes were most sensitive to vaccine cost and coverage.

Conclusion

HPV vaccination is a cost-effective strategy, and should be considered a possible strategy to reduce the impact of HPV infection.

Impact of adoption of chemoradiotherapy on the outcome of cervical cancer in Ontario: results of a population-based cohort study

PURPOSE

To describe the adoption of concurrent cisplatin-based chemoradiotherapy (C-CRT), and to evaluate its impact on the outcome of cervical cancer in Ontario.

METHODS

We used a population-based cancer registry to identify the 4,069 patients with invasive carcinoma of the cervix diagnosed in Ontario between 1992 and 2001. We linked electronic records of treatment to the registry. We described time trends in the use of C-CRT, and we compared survival before and after widespread adoption of C-CRT.

RESULTS

Over the study period, the proportion of patients treated with primary radical radiotherapy (RT) remained constant at approximately 42%. Between 1992 and 1998, less than 10% of RT cases received chemotherapy. Early in 1999, there was rapid adoption of C-CRT. Between 1999 and 2001, more than 60% of RT cases received C-CRT. There was a contemporaneous increase in overall 3-year survival from 71.1% in the 1995 to 1998 cohort to 75.9% in the 1999 to 2001 cohort (P = .03). There was no change in survival in patients treated with surgery alone. However, there was a significant increase in 3-year survival from 58.6% in the 1995 to 1998 cohort to 69.8% in the 1999 to 2001 cohort (P < .01) in the subpopulation of patients treated with primary RT +/- chemotherapy.

CONCLUSION

The adoption of C-CRT was associated with a significant improvement in overall survival of cervical cancer at the population level. The magnitude of the benefit of C-CRT in the general population was consistent with the results of the relevant clinical trials.

Calculating age-adjusted cancer survival estimates when age-specific data are sparse: an empirical evaluation of various methods

We evaluated empirically the performance of various methods of calculating age-adjusted survival estimates when age-specific data are sparse. We have illustrated that a recently proposed alternative method of age adjustment involving the use of balanced age groups or age truncation may be useful for enhancing calculability and reliability of adjusted survival estimates.