Hereditary nonpolyposis colorectal cancer in young colorectal cancer patients: high-risk clinic versus population-based registry.
OBJECTIVE
Early onset colorectal cancer (CRC) is an important feature of hereditary nonpolyposis colorectal cancer (HNPCC). We sought to compare rates of genetically defined HNPCC among individuals with early onset CRC drawn from a high-risk clinic and a population-based cancer registry.


METHODS
Probands with CRC diagnosed before 36 years of age were enrolled from a high-risk CRC clinic at the University of California, San Francisco (UCSF), and a population-based Kaiser Permanente (KP) Health Plan cancer registry. Probands provided cancer family histories and tumors for microsatellite instability (MSI) testing and MSH2/MLH1 protein immunostaining. Germline MSH2 and MLH1 mutational analysis was performed.


RESULTS
Forty-three probands were enrolled from UCSF and 23 from KP. The UCSF and KP probands had similar median age of onset of CRC (30 vs. 31 years) and the percentage with any personal or family history of another HNPCC-related cancer (70% vs. 74%). However, 28 of 40 (70%) of the UCSF tumors were MSI-H compared with 6 of 18 (33%) of KP tumors (P = 0.01), and 13 germline MSH2 or MLH1 mutations were found in the UCSF group compared with 0 in the KP group (P = 0.0001). In a multivariate analysis, institution (P = 0.002) and the total number of colorectal cancers in the family (P = 0.0001) were independent predictors of MSH2 or MLH1 mutation.


CONCLUSIONS
Family history of cancer is an important feature of HNPCC, even among individuals with early onset CRC. Caution must be undertaken when extrapolating data regarding HNPCC from high-risk clinic populations to the general population.
Terdiman
Jonathan P
JP
Department of Medicine, University of California, San Francisco 94143, USA. jterd@itsa.ucsf.edu
Levin
Theodore R
TR
Allen
Brian A
BA
Gum
James R
JR
Fishbach
Andrea
A
Conrad
Peggy G
PG
Miller
Glenn A
GA
Weinberg
Vivian
V
Bachman
Ronald
R
Bergoffen
Joann
J
Stembridge
Ann
A
Toribara
Neil W
NW
Sleisenger
Marvin H
MH
Kim
Young S
YS
D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000554:Ambulatory Care Facilities; D002352:Carrier Proteins; D015179:Colorectal Neoplasms / Q000737:chemistry / Q000453:epidemiology* / Q000235:genetics*; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins; D018095:Germ-Line Mutation; D006801:Humans; D007150:Immunohistochemistry; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000032:analysis / Q000235:genetics; D009687:Nuclear Proteins; D011237:Predictive Value of Tests; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics; D012042:Registries; D012307:Risk Factors
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein