type of tissue where the embryonic cells remain
after organ development. Blastomas nearly always
occur in childhood, though occasionally may
occur in early adulthood. Most blastomas are
malignant (cancerous), though osteoblastoma
(blastoma of the BONE) is a benign (noncancerous)
tumor. Treatment for blastoma typically combines
surgery to remove the tumor with CHEMOTHERAPY,
RADIATION THERAPY, or both to shrink the tumor
before surgery and destroy any lingering cancer
cells after surgery. The precise combination
depends on the tumor’s location and size at the
time of diagnosis.
TYPES OF BLASTOMATumor Location
medulloblastoma BRAIN
nephroblastoma kidney
RETINOBLASTOMA RETINAof the EYE
osteoblastoma BONE
neuroblastoma NERVOUS SYSTEMtissue
glioblastoma multiforme (GBM) brain
See also ADENOCARCINOMA; CARCINOMA; LEUKEMIA;
SARCOMA; SURGERY FOR CANCER; SURGERY BENEFIT AND
RISK ASSESSMENT; WILMS’S TUMOR.
BRCA-1/BRCA-2 BREAST CANCER GENE 1 and
breast cancer gene 2, the first genes in which
researchers identified mutations that correlate to
increased susceptibility to BREASTcancer and OVAR-
IAN CANCER. About one in six women who have
either of these cancers have mutations in either or
both of the genes. Many are women who have a
known family history of breast cancer or ovarian
cancer. The presence of mutations in either of
these genes means a woman has an increased risk
for developing breast or ovarian cancer but it does
not mean cancer is inevitable. Researchers do not
yet know the extent to which BRCA-1/BRCA-2
gene mutations affect a woman’s risk for cancer,
though believe they are responsible for about 5
percent of breast and ovarian cancers. Many fac-
tors influence the development of cancer; genetics
remains only one among them.
Testing for BRCA-1/BRCA-2 is controversial
because there are few preventive or therapeutic
actions women or doctors can take as a result of
knowing a positive result. Under current practice
guidelines, doctors may choose to offer such test-
ing to women who have first-degree relatives
(mother, daughter, sister, grandmother) who have
breast cancer or ovarian cancer or who are them-
selves under age 50 at the time of being diagnosed
with either type of cancer. A positive result (muta-
tions are present) may be a factor in prophylaxis
or treatment decisions, though is by itself not a
strong enough indicator to be the basis for such
decisions. Nor is a negative result any indication
that a woman will not develop breast or ovarian
cancer. Because doctors can detect breast and
ovarian cancers early through regular examina-
tions, most health experts believe such examina-
tions remain the most effective means for early
diagnosis and treatment regardless of genetic
influences.
See also CA- 125 ; GENETIC TESTING; MUTATION;
PROSTATE-SPECIFIC ANTIGEN(PSA).BRCA-1/BRCA-2 369