Gail et al developed a method for predicting the probability of breast cancer in a white woman, with the risk individualized for the patient based on the presence of certain risk factors. The process consists of calculating the relative risk for the patient (this section) and then converting this to the absolute risk for the patient (next section).
Problems identified in estimating the probability of breast cancer:
(1) determining which risk factors are important and estimating the relative risk for a subject with a given constellation of risk factors at a given age, compared to a subject without the identified risk factors.
(2) estimating the baseline age-specific breast cancer hazard rate
(3) projecting long-term probability of developing breast cancer on the basis of competing risks and the results on relative risk and baseline hazard.
Criteria for inclusion:
(1) white female
(2) examined annually
(3) patient does not have a single gene trait that predisposes to breast cancer
(4) does not already have a diagnosis of carcinoma in situ or carcinoma of the breast
Logistic Regression Equation
|
Parameter |
Finding |
Value |
|
age of menarche in years |
>= 14 |
0 |
|
|
12 - 13 |
1 |
|
|
< 12 |
2 |
|
number of biopsies |
0 |
0 |
|
|
1 |
1 |
|
|
>= 2 |
2 |
|
age of first live term birth |
nulliparous |
2 |
|
|
< 20 |
0 |
|
|
20 - 24 |
1 |
|
|
25 - 29 |
2 |
|
|
>= 30 |
3 |
|
number of first degree relatives with breast cancer |
0 |
0 |
|
|
1 |
1 |
|
|
>= 2 |
2 |
|
age at counseling |
< 50 |
0 |
|
|
>= 50 |
1 |
LN(odds ratio for disease) =
= (-0.74948) + (0.09401 * (value for age of menarche)) + (0.52926 * (value for number of biopsies)) + (0.21863 * (value for age at first live term birth)) + (0.95830 * (value for number of first degree relatives for breast cancer)) + (0.01081 * (value for age at counseling)) - (0.28804 * (value for number of biopsies) * (value for age at counseling)) - (0.19081 * (value for age at first live term birth) * (value for number of first degree relatives with breast cancer))
Simplified Method
Parameters:
(1) age at menarche in years
(2) age of counseling and number of breast biopsies
(3) age of first term live birth and number of first degree relatives with breast cancer
(4) presence of atypical hyperplasia in a breast biopsy
|
Parameter |
Finding |
Relative Risk |
|
age at menarche in years |
< 12 |
1.00 |
|
|
12 - 13 |
1.10 |
|
|
>= 14 |
1.21 |
|
age of counseling and number of breast biopsies |
age of counseling < 50 years and 0 biopsies |
1.00 |
|
|
age of counseling < 50 years and 1 biopsies |
1.71 |
|
|
age of counseling < 50 years and >= 2 biopsies |
2.88 |
|
|
age of counseling >= 50 years and 0 biopsies |
1.00 |
|
|
age of counseling >= 50 years and 1 biopsies |
1.27 |
|
|
age of counseling >= 50 years and >= 2 biopsies |
1.62 |
|
age of first term live birth and number of first degree relatives with breast cancer |
age < 20 and 0 first degree relatives |
1.00 |
|
|
age < 20 and 1 first degree relative |
2.61 |
|
|
age < 20 and >= 2 first degree relatives |
6.80 |
|
|
age 20-24 and 0 first degree relatives |
1.24 |
|
|
age 20-24 and 1 first degree relative |
2.68 |
|
|
age 20-24 and >= 2 first degree relatives |
5.78 |
|
|
age 25-29, or nulliparous, and 0 first degree relatives |
1.55 |
|
|
age 25-29, or nulliparous, and 1 first degree relative |
2.76 |
|
|
age 25-29, or nulliparous, and >= 2 first degree relatives |
4.91 |
|
|
age >= 30 and 0 first degree relatives |
1.93 |
|
|
age >= 30 and 1 first degree relative |
2.83 |
|
|
age >= 30 and >= 2 first degree relatives |
4.17 |
|
presence of atypical hyperplasia in a biopsy |
yes |
1.82 |
|
|
otherwise |
0.93 |
(from Table C-10, Offit, page 396; after Table 1, Gail, page 1881)
where:
• The relative risks in this table were obtained from the logistic regression equation above.
total relative risk for the patient =
= (risk from age of menarche) * (risk for counseling age and breast biopsies) * (risk from age of first term live birth and number of first degree relatives) * (risk from known atypical hyperplasia)
Interpretation:
• minimum relative risk: 0.93
• maximum relative risk: 43.13 (1.21 * 2.88 * 6.8 * 1.82)
Specialty: Hematology Oncology, Surgery, general, Obstetrics & Gynecology
