Friday , May 14 2021

Get a clear picture of chemoprevention

Each year, the ways in which doctors can diagnose and treat cancer become more sophisticated.

To date, cancer prevention in primary care has focused on changes in behaviors associated with increased risk of cancer – primary prevention – or increased participation in national cancer screening programs, known as secondary prevention.

The potential harm and benefits of cancer chemoprevention must be clearly explained to patients. Image: Getty Images

But if you are at a higher risk of developing cancer, there are approaches that can prevent it in the first place, known as chemoprevention. Chemoprevention can include the use of drugs to reduce risks, delay development or recurrence of cancer, or even try to prevent it altogether.

Now it goes into general practice for specific groups of patients.

But all drugs have possible side effects and the potential damages and benefits of cancer chemoprevention must be clearly explained to patients. And how these risks and side effects are explained to people.

Researchers from the University of Melbourne Cancer in the primary study group have developed a new method of communicating this information through diagrams called "expected frequency trees".

The team developed the charts to demonstrate the effects of aspirin to reduce the risk of developing bowel cancer in people aged 50 to 70. They also used the expected frequency tree chart to explain the use of drugs called selective estrogen receptor modulators (SERM) for women at increased risk for cancer The demon.

The team examined the clinical implications of relatively new Australian guidelines on prevention, early detection and management of bowel cancer, including a prescription of drugs to reduce colon cancer risk.

The guidelines were published by the National Council for Medical Medical Research in 2017 and were led by the Australian Cancer Council with contributions from Professor John Emery of the University of Melbourne.

Expected frequency trees for women in Australia at moderate risk for breast cancer, showing the effects of taking tamoxifen and raloxifen for five years. Graphic: Provided

Studies have shown that taking aspirin for about two and a half years can reduce the incidence of bowel cancer when those at increased risk for bowel cancer are more likely to benefit than those at the mean risk of bowel cancer.

Overall, studies have found benefits such as reducing the risk of heart attacks and reducing colon cancer, significantly increasing the potential damage from aspirin, such as gastrointestinal bleeding.

It is estimated that for a person who is 50 years old, taking aspirin for 10 years is 10 times more likely to prevent death than to cause it, which is five times more likely for someone 65 years old.

For the study, Prof. Andrew Emery, Dr. Jennifer Walker, Dr. C. Minschel, Ms. & Cara-Lynn Cummings and Mr. Peter Nguyen have introduced new communication methods, including the "expected frequency trees" to show what happens to 10,000 Australian men and women between 50 and 70 years of age who have taken aspirin.

Diagrams – which have stem and branches – show reasonable results for 10 years of taking aspirin for at least five years. These visual summaries aim to present the likelihood of specific outcomes to help patients make more informed decisions about treatment.

It is important to involve patients in the treatment selection process. Image: Getty Images

Peter Nguyen, a doctoral candidate at the primary school cancer group at the University of Melbourne, conducted a study with general patients to assess the risk communication methods, including the expected frequency tree, for the use of aspirin as an outstanding student last year. He noted the importance of patient involvement in the treatment selection process.

"There is a transition to encouraging joint decision making, showing patients the benefits and vulnerabilities to let them know if they want to take cancer prevention drugs," Nguyen said.

"This study clearly shows that the benefits of taking aspirin to prevent colorectal cancer still outweigh any potential harm in the cohort of patients aged 50-70, even over long periods of time."

For breast cancer prevention, several randomized controlled trials have shown that drugs such as tamoxifen and rloxifen (so-called "SERMs") significantly reduce the risk of breast cancer in women who do not have a personal history of the condition.

Data analysis from 9 prevention trials showed a 38% reduction in the incidence of breast cancer. Participants included women at increased risk of breast cancer as well as those at moderate risk, as well as women before menopause and after menopause. Australian guidelines recommend that women with an increased risk of breast cancer, due to their family history, should consider using SERM to prevent breast cancer.

The expected frequency trees aim to show clearly the benefits and side effects of taking three different types of drugs to treat chemoprevention for breast cancer.

The trees show that the decision to take SERM is potentially more complex than for aspirin. Women with a family history of breast cancer wishing to investigate SERMs for chemoprevention may be better referred to as a family cancer clinic or breast cancer specialist service. The discussion of taking aspirin to prevent colorectal cancer can sit well within the initial treatment.

The guidelines for aspirin and SERM reflect a new approach to cancer prevention in primary care.

The decision to prescribe these drugs involves careful discussion with the patient about the potential benefits and injury and consideration of the risks to the disease. Decision trees can be important and effective tools for guiding and communicating vital discussions with patients.

Poster: Shutterstock

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