Codes and Frequencies
For sample adults whose biological mother ever had cancer of any kind (BMHCAN), BMCLCAN reports whether the respondent's biological mother ever had colon cancer.
Beginning in 2015, details about colon cancer (and several other cancer types) were suppressed because of low frequencies of these types of cancer among family members. Cancers of the colon and rectum are not available separately on the NHIS public use files to protect confidentiality; incidence of these cancer types for biological mothers is combined in BMCLRCAN, which reports whether the sample adult's biological mother had ever been diagnosed with colorectal cancer.
BMCLCAN is one of a series of related variables in the "Family History" section of the 2000, 2005, and 2010 Cancer Modules. In all years, this section begins with the general comment:
According to the 2000 and 2005 Field Representative's Manuals, the purpose of this and other family cancer history questions is to "determine the prevalence of cancer in families in the population" to "allow a greater understanding of how data obtained from genetics clinics can be applied to the general population." The 2010 and later Manuals provide a similar rationale, stating that the collection of this data "will allow analysts a greater understanding of how family history relates to cancer.
The Manuals for all years define "biological" relatives as people related by blood. Thus, a respondent's biological mother is a mother related to the respondent by blood (i.e., not a stepmother, adoptive mother, foster mother, or mother-in-law).
BMCLCAN is fully comparable between 2005 and 2010.
BMCLCAN is largely comparable between 2000 and 2005/2010, though there may be some difference in the meaning of "refused," "not ascertained," and "don't know" as used in 2000 compared to the meanings of those terms in 2005 and 2010.
The Survey Descriptions for all three years caution that while "all sample adults were to be asked the questions in the Cancer Control Module, some persons did not complete the supplement." However, whereas in 2000, persons who answered less than 50 percent of the questions in the supplement had a value of "not ascertained" automatically inserted in the appropriate fields of the Cancer Control Module file, in both 2005 and 2010, persons who answered none of the questions in the supplement had a value of "not ascertained" automatically inserted in the appropriate fields of the Cancer Control Module file.
- 2000; 2005; 2010: Sample adults age 18+ whose mother ever had cancer.
- 2000, 2005, 2010
- 2000, 2005, 2010 : SAMPWEIGHT