colon cancer/cimetidine

I HAVE RECENTLY HEARD OF THE USE OF CIMETIDINE (TAGAMET) FOR COLON CANCER TREATMENT. BOTH MY FATHER AND MOTHER HAVE/HAVE HAD COLORECTAL CANCER, MY FATHER UNFORTUNATELY DIED 2 YEARS AGO FROM THE DISEASE AND MY MOTHER IS AT PRESENT RECOVERING FROM SURGERY. BOTH MUM AND DAD TOOK THE DRUG CIMETIDINE WHEN IT FIRST CAME ON THE MARKET FOR MANY YEARS. MY QUESTION IS COULD CIMETIDINE BE A CAUSE OF THIS CANCER BECAUSE IT IS THE ONLY THING I CAN COME UP WITH AS A LINK BETWEEN MUM AND DAD HAVING THE SAME CANCER. I HAVE NOW COME ACROSS ANOTHER 6 COLON CANCER PATIENTS WHO HAVE TAKEN CIMETIDINE IN THE EARLY YEARS. COULD THIS BE TRUE? IS THERE ANY MORE PEOPLE OUT THERE? OR IS THE FACT BOTH MUM AND DAD HAVE THE SAME CANCER A TOTAL COINCIDENCE. I DONT WANT TO SCARE ANYONE SO CAN YOU PLEASE HELP?