A 44 y/o patient has a lump in their chest of about 2 cm in diameter. The patien

Question

A 44 y/o patient has a lump in their chest of about 2 cm in diameter. The patient has a small dimple at the lump. When the lump is manipulated it seems to be attached to the surrounding tissue. A lumpectomy is done. The pathology report shows that the mass is an estrogen receptor negative, a progesterone receptor negative, and a her2/neu receptor positive breast cancer.

A. What are some of the risk factors for breast cancer?

B. What tumor suppressor genes are associated with breast cancer?

C. What tumor oncogenes are associated with breast cancer?

D. Compare and contrast tumor suppressor genes from oncogenes?

Explanation / Answer

A. Ans:

Risk Factors for Breast Cancer:

-Getting older

-Early menstrual period: Women who start their periods before age 12 are exposed to hormones longer, raising the risk for breast cancer by a small amount.

-Having the first pregnancy after age 30 and never having a full-term pregnancy can raise breast cancer risk.

-Genetic mutations

-Older women who are overweight or obese have a higher risk of getting breast cancer than those at a normal weight.

-Women who had radiation therapy to the chest or breasts (like for treatment of Hodgkin’s lymphoma) before age 30 have a higher risk of getting breast cancer later in life.

B. Ans

BRCA1 and BRCA2 mutations are associated with a significantly elevated risk for breast and ovarian cancers. Rare germ-line mutations in TP53 (the gene encoding p53) and PTEN are associated with high risk for various cancers, including breast cancer.

C. Ans:

On Oncogenes and Tumor Suppressor Genes in the Mammary Gland. Breast cancer in humans is associated with genetic alterations of a number of oncogenes (ErbB2, MYC, PIK3CA) and tumor suppressors (TP53, BRCA1/2, RB1, PTEN)

D. Ans:

An important difference between oncogenes and tumor suppressor genes is that oncogenes result from the activation (turning on) of proto-oncogenes, but tumor suppressor genescause cancer when they are inactivated (turned off). But mosttumor suppressor gene mutations are acquired, not inherited.

Oncogenes :

Mutation in one of two alleles is sufficient for activity as an oncogene and often act dominant to wild type.

Mutation often occurs in somatic tissues therefore not inherited

Conversion of protooncogene to oncogene is often a "Gain of Function" of protein that signals uncontrolled cell division

Tumor Suppressor Genes:

Tumour suppressor gene malfunctioning is caused by mutations in both alleles or a mutation in one followed by a loss of or reduction to homozygocity in the second

Mutation may occur in germ cells (can be inherited) or somatic cells

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