Molecular
Diagnostics for
Breast Cancer
Presented by: Sanchita Golder (1939)
CE2 - Mol. Diagnostics
SYBSc. BT
Topic Outline
UNDERSTANDING
CANCER(S)
PRINCIPLE OF FISH
CLINICAL
DIAGNOSTICS
BIBLIOGRAPHY AND
REFERENCES
"Cancer"
Cancer is a debilitating
disease, caused by cells that
divide rampantly and spread
into other tissues.
It is a failure of regular cellular
senescence mechanisms due to
DNA mutations. "Carcinogens"
are a causative for cancer, while
genetic predispositions can be
a factor.
When normal cell replication processes are disrupted due to mutations, they form
lumps of tissue. These may be non-dangerous (benign) or cancerous (malignant)
Benign tumours do not invade other tissues. Cancerous tumours do, thereby
disrupting the normal functioning of the tissues (or organs, then organ systems, then
the whole body.
"Cancer" is a recognisable term for various invasive diseases,
commonly characterised by malignant spread of cells that don't abide
by natural cell death mechanisms (senescence)
However, not all cancers are the same. There are various types of "cancers". Carcinomas, the most common form of
cancer, are formed by epithelial cells. Sarcomas are cancers of bone and soft tissues (muscle, fat, blood vessels, lymph
vessels, and fibrous tissue (such as tendons and ligaments).
Cancers that begin in the blood-forming tissue of the bone marrow are called leukemias. These cancers do not form solid
tumors.
Lymphoma is cancer that begins in lymphocytes (T cells or B cells). In lymphoma, abnormal lymphocytes build up in lymph
nodes and lymph vessels. Multiple myeloma is cancer that begins in plasma cells, another type of immune cell. The
abnormal plasma cells, called myeloma cells, build up in the bone marrow and form tumors in bones all through the body.
So on, and so forth.
Cancer cells migrate
Metastasis is the term for cancer cells
spreading to other body parts.
For example, breast cancer that forms
a metastatic tumor in the lung is
metastatic breast cancer, not lung
cancer.
Diagnostics for Breast Cancer
1. Biopsy
A small amount of tissue
for examination under a
microscope.
3. HER2 Testing
using FISH
A FISH test on breast cancer tissue
removed during a biopsy can show
whether the cells have extra copies
of the HER2/neu gene.
2. Analyzing the
biopsy sample
The HER2 status of the cancer
helps determine whether drugs
that target the HER2 receptor
might help treat the cancer.
BRCA1 & BRCA2
Testing
(Preventive)
Harmful variants in one of these genes have
increased risks of several cancers—most
notably breast and ovarian cancer. They also
tend to develop cancer at younger ages .
FISH (Fluorescence in situ
hybridization)
This test "maps" genetic
material in human cells,
including specific genes or
portions of genes.
Importance
A FISH test on breast cancer tissue removed
during a biopsy can show whether the cells
have extra copies of the HER2/neu gene.
Cells with extra copies of the gene have
more HER2 receptors, which receive signals
that stimulate the growth of breast cancer
cells. So patients with extra copies of the
gene are more likely to respond to
treatment with trastuzumab (Herceptin), a
drug that blocks the ability of HER2
receptors to receive growth signals.
How FISH
Testing works
Principle
Importance
Preparation of fluorescent probes,
that bind (hybridise) to only those
parts with a high degree of
sequence complementarity.
FISH works by exploiting the ability of DNA
strand to bind specifically to another DNA
strand.
EXAMPLE
OF VISUAL
References:
IMMUNE (2021); PHILIPP DETTMER
KUCHENBAECKER KB, HOPPER JL, BARNES DR, ET AL.
RISKS OF BREAST, OVARIAN, AND CONTRALATERAL
BREAST CANCER FOR BRCA1 AND BRCA2 MUTATION
CARRIERS. JAMA 2017; 317(23):2402–2416.
WEBMD- FISH TEST; MEDICALLY REVIEWED BY
DR. CAROL DERSARKISSIAN, MD