Breast carcinoma and Lynch syndrome: molecular analysis of tumors arising in mutation carriers, non-carriers, and sporadic cases.
BACKGROUND
Breast carcinoma is the most common cancer in women, but its incidence is not increased in Lynch syndrome (LS) and studies on DNA mismatch repair deficiency (MMR) in LS-associated breast cancers have arrived at conflicting results. This study aimed to settle the question as to whether breast carcinoma belongs to the LS tumor spectrum.


METHODS
MMR status and epigenetic profiles were determined for all available breast carcinomas identified among 200 LS families from a nation-wide registry (23 tumors from mutation carriers and 18 from non-carriers). Sporadic breast carcinomas (n = 49) and other cancers (n = 105) from MMR gene mutation carriers were studied for comparison.


RESULTS
The proportion of breast carcinomas that were MMR-deficient based on absent MMR protein, presence of microsatellite instability, or both was significantly (P = 0.00016) higher among breast carcinomas from mutation carriers (13/20, 65%) compared to non-carriers (0/14, 0%). While the average age at breast carcinoma diagnosis was similar in carriers (56 years) and non-carriers (54 years), it was lower for MMR-deficient versus proficient tumors in mutation carriers (53 years versus 61 years, P = 0.027). Among mutation carriers, absent MMR protein was less frequent in breast carcinoma (65%) than in any of seven other tumor types studied (75% to 100%). Tumor suppressor promoter methylation patterns were organ-specific and similar between breast carcinomas from mutation carriers and non-carriers.


CONCLUSIONS
Breast carcinoma from MMR gene mutation carriers resembles common breast carcinoma in many respects (for example, general clinicopathological and epigenetic profiles). MMR status makes a distinction: over half are MMR-deficient typical of LS spectrum tumors, while the remaining subset which is MMR-proficient may develop differently. The results are important for appropriate surveillance in mutation carriers and may be relevant for LS diagnosis in selected cases.
Department of Medical Genetics, Biomedicum Helsinki, P,O,Box 63 (Haartmaninkatu 8), University of Helsinki, Helsinki, Finland, FIN-00014. johanna.lotsari@helsinki.fi
Johanna E
JE
Lotsari
Annette
A
Gylling
Wael M
WM
Abdel-Rahman
Taina T
TT
Nieminen
Kristiina
K
Aittomäki
Marjukka
M
Friman
Reino
R
Pitkänen
Markku
M
Aarnio
Heikki J
HJ
Järvinen
Jukka-Pekka
JP
Mecklin
Teijo
T
Kuopio
Päivi
P
Peltomäki
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000235:genetics; D001943:Breast Neoplasms / Q000150:complications / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000150:complications / Q000235:genetics*; D053843:DNA Mismatch Repair / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D006801:Humans; D053842:Microsatellite Instability; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; C497172:MSH2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes