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COSA Medication Guidelines - Clinicians

The data entry component of iPrevent™ asks about breast cancer risk factors including reproductive factors, lifestyle factors and history of previous breast disease, particularly lobular carcinoma in situ or atypical hyperplasia. Family history of breast, ovarian, prostate and pancreas cancer, including age at diagnosis, is collected (if exact ages are not known, estimates can be entered).

Once data entry is complete, iPrevent™ uses the inputted information to estimate breast cancer risk using one of two well validated, evidence-based mathematical algorithms: IBIS(2) and BOADICEA (via CanRisk)(3,4). The iPrevent™ software determines which of these risk calculation algorithms is used based on the risk factor data entered.

A risk category (as defined by Cancer Australia[5]) is calculated from the risk ratio of the estimated iPrevent™ residual lifetime risk to the residual lifetime population risk for a woman of the same age.

Risk categories
  Average risk < 1.5 times population risk
  Moderate risk (Somewhat increased) 1.5 to 3 times population risk
  High risk (Substantially increased) > 3 times population risk

The estimated effect of any risk-reducing intervention is calculated by applying the following reductions to both the residual lifetime risk and the 10-year risk (see footnote):

  • Risk reducing salpingo-oophorectomy prior to age 45 – a 50% reduction is applied
  • Five years of tamoxifen use – a 33% reduction is applied
  • Five years of raloxifene use – a 25% reduction is applied
  • Five year of exemestane or anastrazole use – a 50% reduction is applied

The estimated breast cancer risk is presented as the risk over the next 10 years as well as residual lifetime risk (up to age 80). This risk is presented in 3 ways, as a statistic, as a pictogram, and as a graph, to account for different preferences for risk communication.  The woman’s individual risk is compared to that of an average risk woman of the same age, using age specific breast cancer rates from the Australian Cancer Incidence and Mortality (ACIM), for 2009[6].

After presenting the breast cancer risk, iPrevent™ presents screening and prevention options appropriate to the estimated risk, based on Australian guidelines [5,7]. Options presented may include risk-reducing bilateral mastectomy, risk reducing salpingo-oophorectomy, risk-reducing medication such as tamoxifen, lifestyle modifications such as weight loss and reducing alcohol intake, and breast cancer screening.


Summary of risk reducing options shown according to the risk category:

Risk Reducing Option ShownRecommended Risk Category
Risk reducing mastectomy   High risk category
Risk reducing salpingo-
oophorectomy

  <=45 years of age and High risk category and
  BRCA1/2 mutation

  <=45 years of age and High risk category and
  at least one relative with ovarian cancer
  Risk reducing medication
Premenopausal:

  Moderate risk and age >=35

  High risk
Post menopausal:

  Moderate risk and age >=35

  High risk
Screening:   All women
Lifestyle modifications:   All women

 

Summary of breast screening recommendations:

Risk CategoryAgeBreast Screening Recommendations

  Population risk

  < 40 years

  No screening
  >= 40 and
 < 50 years		   2nd yearly mammograms optional
  through Breastscreen
  > 50 years   2nd yearly mammograms
  recommended
  Moderate risk

  < 40 years

  No screening
  >= 40 years   Annual mammograms recommended
  High risk

  < 25 years

  No screening
  >= 25 and
  < 50 years		   Annual examination and screening -
  mammograms /MRI/US
  >= 50 years   Annual examination and
  mammography
  - MRI not usually recommended

For risk-reducing mastectomy, salpingo-oophorectomy and medication the estimated effect of each option is then presented as a statistic, a pictogram and a graph.

The estimated risk reduction afforded by these strategies is applied according to the following logic (see footnote):

  • Risk reducing mastectomy – 90% reduction
  • Risk reducing salpingo-oophorectomy under age 45 – 50% reduction
  • Five years of tamoxifen– 33% reduction
  • Five years of raloxifene – 25% reduction

See links provided on this web page to view prescribing information for risk reducing medications.

iPrevent generates a printable summary report incorporating the risk factors that were inputted, the estimated residual lifetime breast cancer risks and the risk management options and associated risk reductions.

iPrevent was last reviewed for accuracy in May 2018.

Footnote
References

Related pages

Preventing Cancer with Medications (PCMed) Service – Information for health practitioners

Preventing Cancer with Medications (PCMed) Telehealth Service