Curves exclude the 3 affected family members used to define the Amsterdam-I
criteria. MSI-H indicates microsatellite instability–high; MSI-L, microsatellite
instability–low; MSS, microsatellite stable; SEER, Surveillance, Epidemiology,
and End Results.
Schematic showing the 2 categories of colorectal cancer syndromes, illustrating
that nonpolyposis disorders are heterogeneous but based on tumor biology can
be distinguished as those having defective mismatch repair (Lynch syndrome;
group A) and those with proficient mismatch repair (group B in this study,
called here familial colorectal cancer type X). Diagram excludes syndromes
characterized by hamartomatous/hyperplastic polyposis.*Defined by any
number of pedigree and/or laboratory criteria, including but not limited to
the Amsterdam criteria. Hereditary nonpolyposis colon cancer syndrome is the
term that has traditionally been used in this context, encompassing those
entities that have emerged as distinguishable clinical entities (ie, Lynch
syndrome and familial colorectal cancer type X).
Lindor NM, Rabe K, Petersen GM, Haile R, Casey G, Baron J, Gallinger S, Bapat B, Aronson M, Hopper J, Jass J, LeMarchand L, Grove J, Potter J, Newcomb P, Terdiman JP, Conrad P, Moslein G, Goldberg R, Ziogas A, Anton-Culver H, de Andrade M, Siegmund K, Thibodeau SN, Boardman LA, Seminara D. Lower Cancer Incidence in Amsterdam-I Criteria Families Without Mismatch Repair DeficiencyFamilial Colorectal Cancer Type X. JAMA. 2005;293(16):1979-1985. doi:10.1001/jama.293.16.1979
Author Affiliations: Departments of Medical
Genetics (Dr Lindor), Health Sciences Research (Ms Rabe and Drs Petersen and
de Andrade), and Laboratory Medicine (Dr Thibodeau), and Division of Gastroenterology
(Dr Boardman), Mayo Clinic, Rochester, Minn; University of Southern California,
Los Angeles (Drs Haile and Siegmund); Cleveland Clinic, Cleveland, Ohio (Dr
Casey); Dartmouth Medical School, Hanover, NH (Dr Baron); Mount Sinai Hospital,
University of Toronto, Toronto, Ontario (Drs Gallinger and Bapat and Ms Aronson);
University of Melbourne, Melbourne, Australia (Dr Hopper); McGill University,
Montreal, Quebec (Dr Jass); University of Hawaii Cancer Research Center, Honolulu
(Drs LeMarchand and Grove); Cancer Prevention Program, Fred Hutchinson Cancer
Research Center, Seattle, Wash (Drs Potter and Newcomb); Department of Cancer
Biology, University of San Francisco, San Francisco, Calif (Dr Terdiman and
Ms Conrad); Department of Surgery, Heinrich Heine University, Düsseldorf,
Germany (Dr Moslein); University of North Carolina, Chapel Hill (Dr Goldberg);
University of California, Irvine (Drs Ziogas and Anton-Culver); and Division
of Cancer Control and Population Sciences, Clinical and Genetic Epidemiology
Research Branch, National Cancer Institute, National Institutes of Health,
Bethesda, Md (Dr Seminara).
Context Approximately 60% of families that meet the Amsterdam-I criteria (AC-I)
for hereditary nonpolyposis colorectal cancer (HNPCC) have a hereditary abnormality
in a DNA mismatch repair (MMR) gene. Cancer incidence in AC-I families with
MMR gene mutations is reported to be very high, but cancer incidence for individuals
in AC-I families with no evidence of an MMR defect is unknown.
Objective To determine if cancer risks in AC-I families with no apparent deficiency
in DNA MMR are different from cancer risks in AC-I families with DNA MMR abnormalities.
Design, Setting, and Participants Identification (1997-2001) of 161 AC-I pedigrees from multiple population-
and clinic-based sources in North America and Germany, with families grouped
into those with (group A) or without (group B) MMR deficiency by tumor testing.
A total of 3422 relatives were included in the analyses.
Main Outcome Measures Cancer incidence in groups A and B (excluding the 3 affected members
used to define each pedigree as AC-I) and computed age- and sex-adjusted standardized
incidence ratios (SIRs) using Surveillance, Epidemiology, and End Results
Results Group A families from both population- and clinic-based series showed
increased incidence of the HNPCC-related cancers. Group B families showed
increased incidence only for colorectal cancer (SIR, 2.3; 95% confidence interval,
1.7-3.0) and to a lesser extent than group A (SIR, 6.1; 95% confidence interval,
Conclusions Families who fulfill AC-I criteria but who have no evidence of a DNA
MMR defect do not share the same cancer incidence as families with HNPCC-Lynch
syndrome (ie, hereditary MMR deficiency). Relatives in such families have
a lower incidence of colorectal cancer than those in families with HNPCC-Lynch
syndrome, and incidence may not be increased for other cancers. These families
should not be described or counseled as having HNPCC-Lynch syndrome. To facilitate
distinguishing these entities, the designation of “familial colorectal
cancer type X” is suggested to describe this type of familial aggregation
of colorectal cancer.
Hereditary nonpolyposis colorectal cancer (HNPCC) is a dominantly inherited
syndrome characterized by significantly increased risks for colon cancer as
well as for cancers of the endometrium, stomach, small intestine, hepatobiliary
system, kidney, ureter, and ovary.1,2 Most
studies have not reported increased risks for lung, breast, or prostate cancers
in HNPCC kindreds. Many experts currently use the term HNPCC synonymously
with a hereditary DNA mismatch repair (MMR) gene deficiency, and studies of
cancer risks in the syndrome have generally focused on families with MMR deficiency.
Based on fairly consistent cancer risks in studies of various designs, clinical
screening guidelines have been proposed, focusing especially on screening
for cancers of the colon and endometrium.3- 6 However,
in the broader clinical realm and in some current medical literature, the
term HNPCC continues to be based on pedigree criteria, typically the strict
Amsterdam I criteria (AC-I),7 which have 3
elements: (1) there are at least 3 relatives with histologically verified
colorectal cancer (1 a first-degree relative of the other 2), and familial
adenomatous polyposis should be excluded; (2) at least 2 successive generations
should be affected; and (3) 1 of the relatives’ colorectal cancers should
be diagnosed before age 50 years.
About half of the families with AC-I pedigrees have no evidence of a
heritable DNA MMR defect, either by gene sequencing or tumor phenotyping for
microsatellite instability (MSI), the hallmark of MMR deficiency.8 For this large group of families, cancer risks have
not been studied, and appropriate screening guidelines are unknown.
In the present study, we identified families fulfilling the strict AC-I
criteria and analyzed the family history for cancer incidences, stratified
by evidence of a DNA MMR defect.
Families fulfilling AC-I criteria were collected from 11 sources (1997-2001),
distinguishing between population-based and clinic-based ascertainment. The
majority of families (139 of 161) came from the Colon Cooperative Family Registry,
a National Cancer Institute–supported consortium established in 1997
to create a multinational comprehensive collaborative infrastructure for interdisciplinary
studies in the genetic epidemiology of colorectal cancer (detailed information
about the registry is available at http://epi.grants.cancer.gov/CFR/). Population-based registries were used to identify eligible cases
at the Fred Hutchinson Cancer Research Center, the University of Hawaii Cancer
Research Center, and Cancer Care Ontario. Sites that included both population-
and clinic-based collections were the Mayo Clinic, University of Southern
California Consortium, and Australia. All families identified as fulfilling
the AC-I criteria were eligible for recruitment at each Colon Cooperative
Family Registry site. Additional clinic-based families were identified at
the Mayo Clinic, at the University of California, San Francisco, and in Düsseldorf,
The study was approved by the institutional review board of each institution.
After providing written consent to participate in research, AC-I families
provided a family history, and enrollment of additional relatives began. Efforts
were made to verify reported cancer diagnoses by use of multiple interviews
of family members and by review of medical records, death certificates, pathology
reports, and tumor tissues. Colorectal tumor blocks were tested for MSI using
10 microsatellite loci (4 mononucleotide markers [BAT25, BAT26, BAT40, BAT34C4],
5 dinucleotide markers [D5S346, D17S250, ACTC, D18S55, D10S197], and MYCL).
Tumors were classified as microsatellite instability–high (MSI-H) if
more than 30% of markers demonstrated instability, as microsatellite instability–low
(MSI-L) if 30% or less demonstrated instability, and as microsatellite stable
(MSS) if no marker exhibited instability. If MSI status was not available,
a surrogate for MSI-H was documentation of a definite deleterious mutation
in either the hMLH1 or hMSH2 genes.
Immunohistochemical testing for MMR proteins of MLH1, MSH2, and MSH6 was conducted on all tumors with
a high or low level of tumor MSI.9
As required by the AC-I criteria,7 each
family contained a “triad” of family members with colorectal cancer.
In many families, there were multiple potential triads. To maintain a consistent
reference point, we assigned the core triad to be the one that included the
earliest-generation member (eg, a grandparent-parent-child triad would be
chosen over a parent and 2 offspring). This rule, while arbitrary, was implemented
to ensure consistency of triad assignment among pedigrees.
Pedigrees were classified into 2 groups: those with MSI-H, reflecting
DNA MMR deficiency (group A), and those with MSI-L or MSS, reflecting intact
DNA MMR capacity (group B). Group A corresponds to hereditary MMR deficiency.
We included only families for whom we had a high level of confidence in the
assignment to the 2 groups; ambiguous families were excluded. Consequently:
(1) An MSI test result for at least 1 of the defining triad members was available
for every pedigree included in the analysis. (2) If the 1 tumor that was used
to define the MSI classification of the pedigree was MSI-H and that person
was younger than 60 years at the time of diagnosis, this pedigree was classified
as group A. (3) Pedigrees were excluded from the study if the only MSI analysis
performed for the entire pedigree was in a person older than 60 years and
was MSI-H, because of the high probability with advancing age that these were
due to epigenetic hMLH1 silencing rather than to
germline MMR mutation. (4) Absence of expression of hMLH1 or hMSH2 demonstrated by immunohistochemical
testing in a tumor was an acceptable surrogate for missing MSI data because
of the demonstrated excellent correlation between immunohistochemical and
MSI analyses.9 The same age-related rules were
used for immunohistochemistry as for MSI, per point 3 above. (5) Normal expression
of hMLH1 or hMSH2 demonstrated
by immunohistochemical testing was not used to infer MSI status in the absence
of actual MSI data. (6) If multiple triad members with colorectal cancer had
MSI testing but results were discordant, then that pedigree was excluded.
However, if multiple members with colorectal cancer were MSI-H with consistent
immunohistochemistry results showing loss of expression of a particular MMR
protein between different family members’ tumors, or if there was a
known germline mutation in the triad member, we included this family as MSI-H,
even if there was a relative with an MSS tumor outside the triad. We interpreted
this as an apparent sporadic phenocopy.
Overall, only 12 of 173 pedigrees (7%) were excluded because of our
inability to assign with confidence to groups A or B.
Relatives in the 2 groups of families were included in the cancer-incidence
evaluation analysis. To provide the most conservative interpretation of risks,
all AC-I–defining triad members were excluded from analysis. Relatives
related by blood to all defining triad members were included in the risk calculations.
“Primary-zone relatives” (ie, those at 50% mendelian risk of being
a carrier of a dominant gene carried by each triad member) were defined as
first-degree relatives of any member of the defining triad. “Secondary-zone
relatives” (ie, those at 25% mendelian risk of being a carrier of a
dominant gene carried by each triad member) were defined as second-degree
relatives of any member of the defining triad who was not in the primary zone.
Primary- and secondary-zone relatives so defined were mutually exclusive groups.
The incidence of cancer in the AC-I families was calculated as the ratio
of observed cases to the number of person-years at risk. Person-years were
calculated from age 20 years until the earliest cancer diagnosis or death.
All cancers, except nonmelanoma skin cancers, were recorded.
The standardized incidence ratios (SIRs) of each cancer among members
were calculated as the ratio of the observed to the expected numbers of cases.
The latter was calculated as the sum of the products of the number of person-years
for each 5-year age/sex group and the corresponding age/sex-specific incidence
rates from the Surveillance, Epidemiology, and End Result (SEER) database.10,11 Because individuals in groups A and
B were blood relatives, the SEs in the confidence intervals (CIs) were underestimated
using a standard analytical procedure. To correctly estimate the SEs, a bootstrap
analysis using 1000 replicates12 was run on
all cancers, and 95% CIs were reported from the bootstrap results.
All analyses were stratified by MSI status (group A [MSI-H] vs group
B [MSI-L/MSS]). In addition, analyses were conducted separately in the population-
and clinic-based groups, and in the primary and secondary zones. P values for the difference in cancer incidence between the MSI-H and
the MSI-L/MSS groups were computed.13 Statistical
analyses were performed using SAS version 8 (SAS Institute Inc, Cary, NC); P<.05 was used to determine statistical significance.
After exclusion of the reference triad of each pedigree, 3422 relatives
(1680 women, 1742 men) were included in the analyses, 1657 in the primary
zone and 1765 in the secondary zone. Of these, 518 (15.1%) reported being
diagnosed with cancer, including 438 with 1 tumor, 62 with 2 primary tumors,
17 with 3, and 1 with 4, all of which were counted. There were 90 group A
AC-I pedigrees (46 population-based) with MSI-H, and 71 group B pedigrees
(46 population-based) with either MSI-L (n = 11) or MSS (n = 60).
None of the group B cases had loss of expression of MSH6 demonstrated by immunohistochemical testing.
Table 1 shows that group A relatives
had greatly increased incidences for cancers of the colorectum and uterus
(endometrium), stomach, urinary tract (kidney/ureter), ovary, and small intestine.
There was also evidence for increased incidences for cancers of the pancreas
and liver, but no increases for cancers of the breast, lung, prostate, or
cervix, or for melanoma. In contrast, group B showed increased incidences
only for colorectal cancer, and the SIR was less than half of that seen in
Table 2 presents results stratified
by method of ascertainment. The SIRs in the clinic-based families in group
A were greater than for the population-based families for colorectal cancer
(9.6 [95% CI, 7.5-12.3] vs 4.3 [95% CI, 3.4-5.3], respectively) and for uterine
cancer (5.4 [95% CI, 3.1-7.9] vs 3.4 [95% CI, 1.9-4.8]). In group B, the SIRs
for colorectal cancer were greater in the clinic-based families than in the
population-based families (3.1 [95% CI, 1.9-4.3] vs 2.0 [95% CI, 1.3-2.7]).
Table 3 shows that primary-zone
relatives had greater SIRs overall than secondary-zone relatives. In group
A, the SIRs for cancers of the colorectum, uterus, stomach, kidney, ovary,
and small intestine were all significantly elevated in primary-zone relatives.
In group B, this was true only for colorectal cancer among primary-zone relatives
(2.7 [95% CI, 1.9-3.4]).
The cumulative age-of-onset curves for colorectal cancer among all relatives
in groups A and B, compared with the distribution of colorectal cancer diagnoses
in the SEER data, are shown in Figure 1.
The curves are clearly distinguishable, indicating that relatives in AC-I
families (groups A and B) tend to develop colorectal cancer at a younger age
than the general (ie, SEER) population and that group A relatives tend to
develop colorectal cancer at a younger age (mean, 48.7 years) than group B
relatives (mean, 60.7 years).
We have documented that families fulfilling the stringent AC-I criteria7 without evidence of MMR deficiency have a distinctly
different pattern of cancer incidences than AC-I families that do have MMR
deficiency. The group A families, with presumed hereditary DNA MMR deficiency,
showed cancer incidences that are typical of what has been previously reported:
very high SIRs for cancers of the colorectum, endometrium, stomach, small
intestine, and ureter but no increases in incidence of cancer of the breast,
lung, prostate, or other sites. This is consistent with the majority of literature
on hereditary MMR deficiency. In the absence of evidence of MMR deficiency,
there was only a modest increase in the incidence of colorectal cancer and
no increase in the risk of other malignancies. The literature regarding cancer
risks in AC-I families without MMR deficiency has been very limited but has
hinted that there could be differences from the AC-I families with MMR deficiency.14,15 Thus, in counseling such families,
clinicians can now provide them with more accurate and lower-risk information,
using these new data in combination with the specific family history.
We hypothesize that the AC-I families with no MMR defects are a heterogeneous
group comprised of (1) some cancer aggregation occurring by chance alone,
(2) some aggregation related to shared lifestyle factors, and (3) some yet-to-be-defined
genetic syndromes. Group B families with particularly strong or unusual histories
are best counseled based on a customized assessment of the pedigree, but such
families should not automatically be triaged to HNPCC screening algorithms,
as is current practice.
It is notable that the mean age at diagnosis of colorectal cancer in
group A relatives (48.7 years) was substantially lower than that for group
B relatives (60.7 years), further underscoring the inappropriateness of standard
HNPCC screening guidelines for many group B families. Published cancer screening
guidelines for HNPCC, based on expert opinion and some observational studies,
suggest that annual colonoscopy should begin between ages 20 to 25 years and
that annual endometrial cancer screening by transvaginal ultrasound or endometrial
aspirate should begin at ages 25 to 35 years.3- 6 In
addition, consideration of prophylactic subtotal colectomy and hysterectomy
is suggested. These guidelines do seem appropriate for those families with
hereditary DNA MMR defects, based on abundant and consistent data. However,
these guidelines do not seem indicated for the group B families described
in this study, ie, those with AC-I pedigree but no demonstrable defect in
DNA MMR capacity. It is our opinion that for group B families it may be reasonable
to offer colorectal cancer screening initiated 5 to 10 years prior to the
age of earliest colorectal cancer diagnosis in these families, with frequency
determined by initial findings but no less often than every 5 years. Aggressive
endometrial cancer screening in group B families is not supported by our data.
In families that meet AC-I criteria but in whom tumor MSI testing or genetic
testing is not feasible or informative, screening recommendations should default
to those used for families with hereditary DNA MMR.
One limitation of this study is the possibility of underreporting or
misreporting of cancers. Efforts were made to verify reported cancers, but
this was not always feasible. It is important to note, however, that this
deficiency would affect the group A families to the same extent as the group
B families. The fact that the group A families revealed a profile of incidences
for cancers that are extremely consistent with studies of families with hereditary
MMR gene mutations suggests that underreporting or misreporting is unlikely
to explain the differences between group A and group B.
With such emphasis in this study on distinguishing between families
with and without MSI-H, it is important to consider how clinical risk-assessment
triage based on tumor MSI/immunohistochemical testing could be misleading.
First, phenocopies can happen in any family (eg, an MSS tumor arising as a
sporadic event in a group A family). Second, sporadic MSI-H tumors due to
promoter methylation of hMLH1 can arise at any age,
and tumor testing cannot distinguish this finding from MSI-H related to germline
mutation of hMLH1.16 Third,
there are genes involved in the DNA MMR pathway whose mutation only inconsistently
results in an MSI-H tumor (hMSH6, hPMS2).17,18 Additional
laboratory testing can be useful in resolving these uncertainties. Use of
immunohistochemistry for these gene products can be of great help in defining
genetic causality. Testing tumors from multiple affected family members is
also a very powerful way to clarify genetic etiology in AC-I families. Genetic
testing is available for hMLH1, hMSH2, and hMSH6. All these perspectives underscore the imperative
for individualizing cancer risk assessment for AC-I families in whom no DNA
MMR defect can be found.
The use of HNPCC as a label needs to be refined or made obsolete. The
term HNPCC encompasses considerable heterogeneity and has come to mean different
entities to different people. We prefer the term “Lynch syndrome”
or “HNPCC-Lynch syndrome” to specify those individuals or families
with germline mutations in the DNA MMR genes. As diagnostic and clinical studies
are refined, we envision variants described as Lynch syndrome-MLH1, Lynch syndrome-MSH2, and so on (Figure 2). It may be reasonable to introduce
a term for families similar to our group B families, who have a clustering
of colorectal cancer but in whose tumors no DNA MMR gene defect is evident.
We suggest the term “familial colorectal cancer type X.” This
term does not define this group as having hereditary colorectal cancer (which
usually implies single-gene etiology), and it acknowledges our lack of understanding
of the etiology (thus the “X”). As additional single-gene disorders
are discovered in this group, the remaining families with unexplained cancer
etiology can retain the familial colorectal cancer type X designation until
the etiology is explained. Regardless of what term is eventually adopted,
it is essential that the term HNPCC not be used without clearly defining it,
to acknowledge that families with Lynch syndrome (hereditary DNA MMR deficiency)
and those with familial colorectal cancer type X are not equivalent entities.
Corresponding Author: Noralane M. Lindor,
MD, Mayo Foundation, 200 First St SW, Rochester, MN 55905 (firstname.lastname@example.org).
Author Contributions: Dr Lindor had full access
to all of the data in the study and takes responsibility for the integrity
of the data and the accuracy of the data analysis.
Study concept and design: Lindor, Rabe, Petersen,
Goldberg, de Andrade, Boardman.
Acquisition of data: Lindor, Rabe, Petersen,
Baron, Gallinger, Aronson, Hopper, Jass, LeMarchand, Grove, Potter, Newcomb,
Terdiman, Conrad, Moslein, Goldberg, Anton-Culver, Thibodeau, Boardman.
Analysis and interpretation of data: Lindor,
Rabe, Petersen, Haile, Casey, Baron, Bapat, Hopper, LeMarchand, Potter, Newcomb,
Goldberg, Ziogas, de Andrade, Siegmund, Seminara.
Drafting of the manuscript: Lindor, Rabe, Petersen,
Baron, Hopper, Moslein, Anton-Culver.
Critical revision of the manuscript for important
intellectual content: Lindor, Rabe, Petersen, Haile, Casey, Baron,
Gallinger, Bapat, Aronson, Hopper, Jass, LeMarchand, Grove, Potter, Newcomb,
Terdiman, Conrad, Moslein, Goldberg, Ziogas, de Andrade, Siegmund, Thibodeau,
Statistical analysis: Lindor, Rabe, Haile,
Ziogas, de Andrade, Siegmund.
Obtained funding: Lindor, Petersen, Gallinger,
Hopper, Jass, LeMarchand, Grove, Potter, Newcomb, Seminara.
Administrative, technical, or material support:
Lindor, Petersen, Casey, Hopper, Jass, Goldberg, Anton-Culver, Thibodeau,
Study supervision: Lindor, Petersen, Hopper,
Financial Disclosures: None reported.
Funding/Support: This work was supported by
the National Cancer Institute, National Institutes of Health, under RFA CA-95-011
and through cooperative agreements with the members of the Colon Cancer Family
Registry and principal investigators.
Role of the Sponsors: The National Cancer Institute
and the Colon Cancer Family Registry had no role in the design and conduct
of the study; in the collection, analysis, and interpretation of the data;
or in the preparation, review, or approval of the manuscript.
Disclaimer: The content of this article does
not necessarily reflect the views or policies of the National Cancer Institute
or any of the collaborating centers in the Cooperative Family Registries,
nor does mention of trade names, commercial products, or organizations imply
endorsement by the US government or the Cooperative Family Registry. Collaborating
centers include the Australian Colorectal Cancer Family Registry (UO1 CA097735),
the USC Familial Colorectal Neoplasia Collaborative Group (UO1 CA074799),
Mayo Clinic Cooperative Family Registry for Colon Cancer Studies (UO1 CA074800),
Ontario Registry for Studies of Familial Colorectal Cancer (UO1 CA074783),
Seattle Colorectal Cancer Family Registry (UO1 CA074794), University of Hawaii
Colorectal Cancer Family Registry (UO1 CA074806), and University of California,
Irvine Informatics Center (UO1 CA078296).
Acknowledgment: We thank the many families
who have participated in research studies that facilitated this specific study.
We also thank the following individuals for their assistance in this study:
Kristin Lee, John Hake, Hema Vankayala, MD, Robert Vierkant, MAS, and Duncan