Risk evaluation tools - a brief introduction
A number of tools have been developed for statistically evaluating for a healthy woman
the chances that she may get afflicted with breast cancer at a later date. Such an
assessment of risk has proved useful for health services related to preventive and
prophylactic cancer care. The tools are based on mathematical models that express the
relative risk in terms of certain parameters of personal health and the incidence of
disease in closely related family members. The mathematical models, in turn, are derived
from analyses of large amounts of data collected from patients as well as healthy
volunteers joining long term health study projects.
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There are several medical procedures related to prevention and early detection of
breast cancer that have conflicting benefits and disadvantages and require an informed
decision whether to undergo the procedure or not. These procedures include:
1) postmenopausal hormone replacement therapy, 2) mammographic screening, 3) use of
tamoxifen to prevent breast cancer, 4) prophylactic mastectomy to prevent breast cancer,
and, 5) gene screen to look for mutations in BRCA1 and BRCA2.
Armstrong, Eisen, and Weber
have discussed in detail how a quantitative estimate of breast cancer risk helps make a
decision in the above situations.
Originally breast cancer was considered a single disease entity. However, it has come
to light that breast cancers can be classified into etiologically different sub-types
characterized by the presence or absence of an estrogen binding protein in the tumor.
These two types are called ER+ (estrogen receptor positive) and ER- (estrogen receptor
negative), respectively. The prognosis of disease progress as well as the preferred
treatment regimen are drastically different for the ER+ and ER- sub-types of breast
cancer. Breast cancers can similarly be differentiated into PR+ and PR- sub-types
based on whether they contain a receptor protein for the hormone progesterone or not.
On the whole breast cancers fall into one of four sub-types (ER+/PR+, ER+/PR-, ER-/PR+,
and ER-/PR-) based on their hormone receptor status.
While the tools currently available on the Internet evaluate risk of breast cancer
as a single entity, the present tool
(Que sera)
evaluates the risk separately for each sub-type of breast cancer characterized by
hormone receptor status. This provides an opportunity to be better prepared and also
to reduce the risk to the extent possible by changing the controllable risk factors
targeting the sub-type having the largest likelihood. Among the uses of risk calculation
listed above, decisions regarding postmenopausal hormone replacement therapy and the
use of tamoxifen to prevent breast cancer get more significant inputs from a tool like
the present one.
The present tool is based on
Colditz' model of calculation of risk of breast cancers of different hormone receptor
statuses derived from an analysis of data from the Nurses' Health Study
(NHS)
The calculation of risk of breast cancers of different receptor statuses is naturally more incisive
than other methods that calculate the risk of breast cancer as a consolidated entity. However, we
have attempted to design this tool keeping the ease of use as a principal objective. As of now
this tool is made available with the objective of receiving evaluation and feed-back from
qualified physicians and risk evaluation experts (also please read Terms of Use at the
bottom). It is hoped that the tool will soon emerge as an application widely accepted by
family physicians, counselors and doctors in primary health care centers.
Uses of risk evaluation
The Que sera risk evaluation tool - What is new?
Theoretical framework
Design objective