▁also ▁been ▁associated ▁with ▁Lyn ch ▁synd rome , ▁although ▁this ▁relationship ▁is ▁not ▁entirely ▁understood . ▁ ▁Two - third s ▁of ▁colon ▁can cers ▁occur ▁in ▁the ▁proxim al ▁colon . ▁The ▁mean ▁age ▁of ▁col ore ct al ▁cancer ▁diagn osis ▁is ▁ 4 4 ▁for ▁members ▁of ▁families ▁that ▁meet ▁the ▁Amsterdam ▁criteria . ▁The ▁average ▁age ▁of ▁diagn osis ▁of ▁end omet rial ▁cancer ▁is ▁about ▁ 4 6 ▁years . ▁Among ▁women ▁with ▁H NP CC ▁who ▁have ▁both ▁colon ▁and ▁end omet rial ▁cancer , ▁about ▁half ▁present ▁first ▁with ▁end omet rial ▁cancer , ▁making ▁end omet rial ▁cancer ▁the ▁most ▁common ▁sent in el ▁cancer ▁in ▁Lyn ch ▁synd rome . ▁In ▁H NP CC , ▁the ▁mean ▁age ▁of ▁diagn osis ▁of ▁g astr ic ▁cancer ▁is ▁ 5 6 ▁years ▁of ▁age ▁with ▁int est inal - type ▁ad en oc arc in oma ▁being ▁the ▁most ▁commonly ▁reported ▁path ology . ▁H NP CC - associ ated ▁o var ian ▁can cers ▁have ▁an ▁average ▁age ▁of ▁diagn osis ▁of ▁ 4 2 . 5 ▁years - old ; ▁approximately ▁ 3 0 % ▁are ▁diagn osed ▁before ▁age ▁ 4 0 . ▁ ▁A ▁large ▁follow ▁up ▁study ▁( 3 1 1 9 ▁patients ; ▁average ▁follow ▁up ▁ 2 4 ▁years ) ▁has ▁found ▁significant ▁variation ▁in ▁the ▁cancer ▁rates ▁depending ▁on ▁the ▁mut ation ▁involved . ▁Up ▁to ▁the ▁age ▁of ▁ 7 5 ▁years ▁the ▁ris ks