Extent of Pedigree Required to Screen for and Diagnose Hereditary Nonpolyposis Colorectal Cancer: Comparison of Simplified and Extended Pedigrees.

Heo Y1, Kim MH1, Kim DW1, Lee SA1, Bang S1, Kim MJ1, Oh HK1, Kang SB1, Kang SI2, Park JW3, Ryoo SB3, Jeong SY3, Park KJ3.

Author information

1: Department of Surgery, Seoul National University Bundang Hospital, Seongnam, Korea.
2: Department of Surgery, Yeongnam University Hospital, Daegu, Korea.
3: Department of Surgery, Seoul National University Hospital, Seoul, Korea.

Abstract

BACKGROUND:

Obtaining an accurate pedigree is the first step in recognizing a patient with hereditary nonpolyposis colorectal cancer, or Lynch syndrome. However, lack of standardization of the degree of relationship included in the pedigrees generally limits obtaining a complete and/or accurate pedigree.

DESIGN:

This study analyzed the extent of pedigree required to screen for colorectal cancer and to diagnose Lynch syndrome.

SETTINGS:

The study was conducted at 2 tertiary care centers.

PATIENTS:

A detailed family history was obtained from patients undergoing surgery for colorectal cancer from 2003 to 2016. A simplified pedigree that included only first-degree relatives was obtained and compared with the extended pedigree.

MAIN OUTCOME MEASURES:

The eligibility of the 2 pedigrees was assessed for each proband. The proportion of patients who would be missed using a simplified rather than an extended pedigree was calculated based on the American Cancer Society guidelines for recommending screening for colorectal cancer, on the revised Bethesda guidelines and the revised suspected hereditary nonpolyposis colorectal cancer criteria for screening for hereditary colorectal cancer, and on the Amsterdam II criteria for diagnosis of Lynch syndrome.

RESULTS:

The study examined 2015 families, including 41,826 individuals. Use of simplified and extended pedigrees was comparable in screening for colorectal cancer, with ratios of 183 of 185 (98.9%) for American Cancer Society guidelines, 295 of 295 (100%) for revised Bethesda guidelines, and 60 of 60 (100%) for revised suspected hereditary nonpolyposis colorectal cancer criteria. However, the use of simplified pedigrees missed a definitive diagnosis of Lynch syndrome in 6 of 10 patients fulfilling Amsterdam II criteria based on extended pedigrees. The mean ages at diagnosis of the 4 probands included and the 6 missed using simplified pedigrees differed significantly (60.8 vs 38.2 y).

LIMITATIONS:

The study was limited by its recall bias, cross-sectional nature, lack of germline testing, and potential inapplicability to the general population.

CONCLUSIONS:

A simplified pedigree is acceptable for selecting candidates to screen for hereditary colorectal cancer, whereas an extended pedigree is still required for a more precise diagnosis of Lynch syndrome, especially in younger patients. See Video Abstract at http://links.lww.com/DCR/B97.