Mismatch repair gene defects contribute to the genetic basis of double primary cancers of the colorectum and endometrium.
Hereditary non-polyposis colorectal cancer (HNPCC) is a dominantly inherited cancer syndrome caused by germline defects of mismatch repair (MMR) genes. Endometrial cancer is the most common extracolonic neoplasm in HNPCC and is the primary clinical manifestation of the syndrome in some families. The cumulative incidence of endometrial cancer among HNPCC mutation carriers is high, estimated to be from 22 to 43%. We hypothesized that women with double primary cancers of the colorectum and endometrium are likely to be members of HNPCC families. In order to determine how frequently HNPCC manifests in the context of double primary cancers, we examined alterations of two MMR genes, hMSH2 and hMLH1, in 40 unrelated women affected with double primary cancers. These cases were identified using hospital-based and population-based cancer registries in Ontario, Canada. MMR gene mutations were screened by single-strand conformation polymorphism analysis and confirmed by direct sequencing. Eighteen percent (seven of 40) were found to harbor mutations of one of the two MMR genes. Analysis of colorectal and/or endometrial tumors of mutation-negative probands found microsatellite instability in seven of 20 cases. Six of seven mutation-positive probands had strong family histories suggestive of HNPCC. First degree relatives of mutation-positive probands had a very high relative risk (RR) of colorectal cancer (RR = 8.1, CI 3. 5-15.9) and endometrial cancer (RR = 23.8, CI 6.4-61.0). The relative risk of mutation-negative cases was 2.8 (CI 1.7-4.5) for colorectal cancer and 5.4 (CI 2.0-11.7) for endometrial cancer. We recommend that all double primary patients with cancers at these sites should have a genetic evaluation, including molecular analysis for HNPCC where appropriate.
Millar
A L
AL
Department of Pathology and Laboratory Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Pal
T
T
Madlensky
L
L
Sherman
C
C
Temple
L
L
Mitri
A
A
Cheng
H
H
Marcus
V
V
Gallinger
S
S
Redston
M
M
Bapat
B
B
Narod
S
S
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D020137:Base Pair Mismatch / Q000235:genetics; D002352:Carrier Proteins; D015179:Colorectal Neoplasms / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics; D004260:DNA Repair / Q000235:genetics; D004268:DNA-Binding Proteins; D016889:Endometrial Neoplasms / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics*; D009378:Neoplasms, Multiple Primary / Q000235:genetics*; D009687:Nuclear Proteins; D010375:Pedigree; D011518:Proto-Oncogene Proteins / Q000235:genetics*
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