Selection: A patient with a colorectal carcinoma or adenoma.
Purpose: To determine if the person should be tested for MSI.
Original guidelines - testing for MSI is done if the patient:
(1) is from a family with cancer that meets the Amsterdam criteria
(2) has 2 HNPCC-related cancers (see below)
(3) has a colorectal cancer and a first degree relative with
(3a) a colorectal cancer and/or HNPCC-related extracolonic cancer diagnosed at < 45 years of age and/or
(3b) a colorectal adenoma diagnosed at < 40 years of age
(4) has colorectal cancer or endometrial cancer diagnosed at an age < 45 years
(5) has a right-sided colorectal cancer with a solid or cribriform pattern on histopathology diagnosed at an age < 45 years
(6) has a signet-ring type colorectal cancer diagnosed at an age < 45 years
(7) has colorectal adenomas diagnosed at an age < 40 years
Revised guidelines - testing for MSI should be done if the patient:
(1) has a colorectal cancer diagnosed at < 50 years of age
(2) has a synchronous or metachronous HNPCC-associated tumor (including another colorectal cancer, see below) regardless of age
(3) has a colorectal cancer with the MSI-H histology diagnosed at < 60 years of age
(4) has >=1 first degree relative with a colorectal cancer or HNPCC-associated tumor diagnosed < 50 years
(5) has >=2 first or second degree relatives with colorectal cancer or HNPCC-associated tumor diagnosed at any age
where:
• A tumor with a solid or cribriform pattern indicates a poorly differentiated or undifferentiated carcinoma composed of irregular, solid sheets of large, eosinophilic cells with or without small gland-like spaces.
• A signet ring cell carcinoma should be composed of > 50% signet ring cells.
• MSI-H histology is the presence of tumor infiltrating lymphocytes, Crohn's disease like lymphocytic reaction, mucinous or signet ring cell differentiation, or medullary growth pattern.
HNPCC-related cancers include:
(1) synchronous and metachronous colorectal cancer
(2) adenocarcinoma of endometrium, ovary, stomach, biliary tract, pancreas, or small bowel
(3) transitional cell carcinoma of renal pelvis or ureter
(4) sebaceous gland adenomas or keratoacanthomas in Muir-Torre syndrome
(5) brain tumor (usually glioblastoma in Turcot syndrome)
