Resources for Clinicians

iPrevent is a web-based computer application designed to estimate a woman’s breast cancer risk and then provide breast cancer screening and prevention information that is personalised to that woman.

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[1] and BOADICEA [2,3] . 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[4]) 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
  • 5 years of tamoxifen use – a 33% reduction is applied
  • 5 years of raloxifene use – a 25% reduction is applied
  • 5 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[5].

After presenting the breast cancer risk, iPrevent presents screening and prevention options appropriate to the estimated risk, based on Australian guidelines [4,6]. 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
  • 5 years of tamoxifen– 33% reduction
  • 5 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:
This method is only approximate, since these interventions should multiply breast cancer incidence rather than residual lifetime risk.  For a woman with high pre-intervention risk, this approximation can underestimate her post-intervention residual lifetime risk, especially for young women.  In absolute terms, the underestimation of residual lifetime risk, where it occurs, is at worst no more than 9 percentage points for tamoxifen and 3 percentage points for mastectomy.  However, the approximation is very accurate for calculating the post-intervention residual lifetime risks of women with average or moderate pre-intervention risks, and also for calculating the post-intervention 10-year risks of all women, regardless of their pre-intervention risks.
REFERENCES:
  1. Tyrer J, Duffy SW, Cuzick J (2004). A breast cancer prediction model incorporating familial and personal risk factors. Statistics in Medicine. 23(7):1111-30.
  2. Lee AJ, Cunningham AP, Kuchenbaecker KB, Mavaddat N, Easton DF, Antoniou AC, Consortium of Investigators of Modifiers of BRCA1/2, Breast Cancer Association Consortium (2014). BOADICEA breast cancer risk prediction model: updates to cancer incidences, tumour pathology and web interface. British Journal of Cancer. 110(2):535-45.
  3. Antoniou AC, Cunningham AP, Peto J, Evans DG, Lalloo F, Narod SA, Risch HA, Eyfjord JE, Hopper JL, Southey MC, Olsson H, Johannsson O, Borg A, Pasini B, Radice P, Manoukian S, Eccles DM, Tang N, Olah E, Anton-Culver H, Warner E, Lubinski J, Gronwald J, Gorski B, Tryggvadottir L, Syrjakoski K, Kallioniemi OP, Eerola H, Nevanlinna H, Pharoah PD, Easton DF (2008). The BOADICEA model of genetic susceptibility to breast and ovarian cancers: updates and extensions. British Journal of Cancer. 98(8):1457-66
  4. Cancer Australia (2010). Advice about familial aspects of breast cancer and epithelial ovarian cancer (accessed September 2015).
  5. Australian Institute of Health and Welfare (AIHW) (2012). Australian Cancer Incidence and Mortality (ACIM) workbooks (accessed September 2015).
  6. eviQ Cancer Treatments Online (accessed December 2016).