Only about 5% of cancers are linked to the inheritance of mutated genes. These abnormal
genes are present in every cell in the body, including the cells without cancer.
Since each parent provides one of the two copies of most genes, if both genes
are normal, acquiring two mutations is less likely and would usually take more time
than acquiring the one new mutation that would be needed to cause a cancer if one
gene is already abnormal. Cancers caused by inherited gene mutations that increase
cancer susceptibility tend to occur earlier in life. When cancers are of an uncommon
type, if they occur at younger ages than is usual, in a sex that is not usually
affected (for example breast cancer in a male) or also occur in a close relative, like
a parent or sibling, they are more likely to be caused by a family cancer syndrome.
The well-known actor Angelina Jolie brought worldwide attention to the Hereditary
Breast and Ovarian Cancer (HBOC) syndrome when she chose to undergo a bilateral
mastectomy to reduce her risk of cancer because she carried the BRCA1 gene.
The lifetime risk for women of developing breast cancer in the general population
is about 12%. Women with BRCA1 gene mutations have a 50% to 70% chance of
developing breast cancer and a 39% to 46% chance of developing ovarian cancer by
age 70. Women with a BRCA2 gene have a breast cancer risk of 40% to 60% and an
ovarian cancer risk of 11% to 27%.136 The HBOC syndrome can also increase the
incidence of fallopian tube cancer, primary peritoneal cancer, male breast cancer,
pancreatic cancer, prostate cancer, and some other cancers.
A recent study found that breast cancer risk for women under age 40 with mutations
of a third gene PALB2 was higher than among the general population, with a 14%
chance of developing breast cancer by age 50 and a 35% chance of developing the
disease by age 70. The study also found that individuals with PALB2 mutations had
more than twice the risk of ovarian cancer compared with the general population.
A different inherited syndrome, hereditary non-polyposis colorectal cancer (HNPCC),
or Lynch syndrome, greatly increases a person’s risk for colon cancer, with the
cancer often occurring before age 50. HNPCC also leads to a high risk of endometrial
cancer, cancer of the ovary, stomach, small intestine, pancreas, kidney, brain,
ureters, and bile duct. In another syndrome that increases the risk of colon cancer
called familial adenomatous polyposis, hundreds of polyps are seen in the colon.
Li-Fraumeni syndrome is another familial cancer syndrome that can lead to the
development of a number of cancers, most often in childhood. The list of cancers
includes sarcoma, leukemia, central nervous system cancers, cancer of the adrenal
cortex, and breast cancer.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel.