CANCER PREVENTION INSTITUTE OF CANADA

Last updated: 15-Jan-2007

Conclusions and Recommendations

A number of key insights and conclusions offered throughout the report will be collected here for convenience; some the comments may serve as recommendations for policy-makers and planners.

Burden and Trends

Although some infection-related cancers are dropping in incidence, various factors are keeping the prevalence and mortality burden of these diseases at a high level in the Canadian population. Complacency is not an option. Some have suggested that, following tobacco use, infections as a group may be the most significant arena for preventive measures in cancer control.

Uncertainty and Action

The complexity of working out disease mechanisms and interpreting epidemiological data means that confirmed causality relationships between infectious agents and cancer emerge very slowly. As some of the cancers implicated represent such a serious burden for patients and the health care system, however, planners may need to act in the face of uncertain data.

Levels of Prevention

Emphasising the foundation or base of the prevention hierarchy is important. This means intervening to limit the exposure to the pathogen in the first place. If such early primary prevention is not practical or successful, then classic primary prevention must be pursued; with infections, the “gold standard” approach is prophylactic vaccines which prevent any exposure from becoming a serious problem. Finally, if infection does become established and is not expected to resolve spontaneously, then measures need to be taken to ensure that cancer does not develop; sometimes detecting precancerous cells and lesions through screening programs is the beginning of such secondary prevention.

Cost Considerations

A concerted attack across the prevention levels may be required to ultimately control a disease within a population. A complicating factor is that some interventions are more cost-effective than others. For example, there is debate about whether testing for HPV (to prompt primary prevention, if possible) is worth the expense, especially in reference to highly effective cytological screening, which detects precancer or the early stages of cervical cancer and then prompts appropriate secondary prevention. Likewise, though early intervention at the level of transmission is probably preferable, effective vaccines may be as effective as and less costly than preventing exposures to what are sometimes ubiquitous and easily transmitted organisms.

A Key Focus: Sexually Transmitted Infections

The strategies at each of the prevention levels just described should be as comprehensive and aggressive as necessary. Since many of the pathogens covered in this report are sexually transmitted, much of the discussion of early primary prevention revolved around reducing risky behaviours related to sexual activity. This is a crucial area of public health, albeit a sensitive one.

As a framework for the specific programs noted in the report, the list below provides the typical behavioural intervention categories. Understanding the “landscape” of potential interventions provides a context for particular initiatives that have been tried and tested for the various agents. This taxonomy of measures also might suggest some new directions for a jurisdiction to consider if they are aiming towards a truly comprehensive strategy.

Ongoing Investment in Research and Pilot Projects

It is clear that more needs to be known about the transmission of the various pathogens, the co-factors which may be part of initiating and maintaining carcinogenesis, and the overall course of disease. Greater insight into any of these areas will allow enhancements of the prevention armamentarium, ultimately allowing the disease burden to be reduced and, perhaps, eradicated. The dramatic drop in cervical cancer rates, primarily as a result of screening programs, spurs on public health efforts and holds out hope for similar results with other diseases. The development and imminent launch of vaccines for HPV promises a brand new era for cervical cancer prevention, though many implementation questions remain unanswered. Intense resources will be required to encourage other research frontiers, including a vaccine for HIV.

Finally, continued study of other potential etiologic agents is vital in the overall battle against cancer; the potential for disease prevention represented by each of the candidate pathogens makes this a truly exciting area of medical research.

The Temptation of Technology

As captivating as new health technologies can be, it is also important to continue focusing on the classic “low-tech” public health options related to early primary prevention, including initiatives involving media advocacy, education and counselling. The modest record of progress in this regard, even with high-profile agents such as HIV, is very sobering. Much more needs to be done.

Planners also need to be wary of inappropriately supplanting old technologies with new. For instance, some authorities are suggesting that a new HPV vaccine should work alongside rather than replace screening programs, at least until the backlog of potential cervical cancer cases is cleared. The latency period involved can be up to 20 years.

It is clear that a strong coalition between researchers, clinicians, public health managers and funders will be required to navigate through the complex data and policy options and see the sort of breakthroughs desired with the significant cancers described in this report.