I am truly sorry to hear that you lost your mother when you were so young. It's clear that her early death made quite an impact on you, and I do understand how you might fear your annual mammograms.
It is important to know the fact that your mom had breast cancer. That fact alone may increase your risk, if she or her mother also had breast cancer, or if other family members had breast or ovarian cancer. It would be an indication that the BRCA mutation might run in your family and if it does, you might consider genetic testing. Be sure your doctor knows this part of your health history.
There Isn't Always a Family Resemblance
Mothers and daughters can develop different types of breast cancer - so knowing the exact diagnosis is not the most important detail. She may have been diagnosed at a late stage of cancer, or the tumor may have been aggressive. Keep in mind that most cases of breast cancer are NOT hereditary. And remember that detection and treatments have improved greatly in the last 30 years.
Looking Into the Past
If you are still curious about your mother's diagnosis, try asking family members what they remember. Start with close relatives - her siblings, first-degree cousins, and her father's side of the family. If you like, ask your father for his recollections of that time. Relatives may remember certain details about her case, like the stage, diagnosis, treatments, or surgeries. You might try asking for the name of her doctor, and see if you can find any clues that way. Be warned that clinics and hospitals probably won't divulge health records, and when files are 30 years old, they may be in an offsite archive.
Live Healthy Right Now
What matters most with your own health is this: Stay vigilant. Take charge and lower your own risk. Make sure your healthcare team knows that your mother had this disease. Don't skip annual screenings. Live as healthy a life as you can manage. Enjoy each day that you feel well and are well. Refuse to live in fear. More and more of us are surviving this disease, finding it earlier, treating it more effectively. Don't define yourself by your health history or your mammogram results. You're much more than that!
Defeat Your Fear of Mammograms
As for fear of mammograms, I'm with you there. Since you've kept current on screening, chances are that if anything shows up, the best outcome would be "no cancer" and perhaps if a lump is found - it would be tiny and could be successfully treated. That's what I tell myself when I go for my annual squish and squeeze - if it comes back, I'll deal with it - and if stays away, I'll be grateful for another year.
"Genetic Testing for Breast and Ovarian Cancer Risk." Cancer.gov. 20 Mar. 2006. National Cancer Institute. 27 June 2008.
"What Is Hereditary Breast Ovarian Cancer (HBOC) Syndrome?" Cancer.Stanford.edu. 2008. Stanford University. 27 June 2008.
SEER Stat Fact Sheets: Breast. Incidence & Mortality. SEER Cancer Statistics Review, 1975-2007. Surveillance Epidemiology and End Results. National Cancer Institute. Updated in 2010.