What is cancer?

Cancer is a condition where some of our cells are damaged and cannot be repaired by our body. These cells begin to grow and divide abnormally and escape our body's normal control processes. These abnormal cells are cancer cells.

Cancer cells can grow together as masses called tumors which replace normal cells in tissue or organs. These tumors can interfere with the normal functioning of the organ where they arose, and can also spread to surrounding tissue or through the blood and lymph tissue to other organs. When cancer cells spread beyond their original site to other organs it is called "metastasis."

Cancer usually develops slowly, often involving multiple steps (damage to multiple genes), over a period of several years.

    Cancer is a disease of the genome

All cancers arise as a result of changes that have occurred in the DNA sequence of the genomes of cancer cells. The mutations found in a cancer cell genome have accumulated over the lifetime of the cancer patient. DNA in normal cells is continuously damaged by mutagens of both internal and external origins. Most mutations do not lead to cancer. However, when a single cell acquires a set of sufficiently advantageous mutations, called ‘driver’mutations, this allows it to proliferate autonomously, invade tissues and metastasize, result in cancer development.

Cancer is also an evolutionary process.In disease progression, cancer cells are undergoing continuous division and proliferation. Cancer genome is unstable and accumulates many mutations in DNA replications..

One set of important mutations confer resistance to cancer therapy. These are typically found in cancers that have initially responded to treatment but that are now resistant, manifesting as a recurrence.

    Cancer is a heterogeneous disease

Cancer is a heterogeneous disease. Heterogeneity in cancer is not limited to differences between different patients, but also occurs within a single patient. This intrapatient or intratumoral heterogeneity can introduce significant challenges in designing effective treatment strategies.

In theory, there isn't any two cancers that are exactlly same in the world. In disease progression, cancer cells are undergoing continuous division and proliferation, which results in different cancer cells that can show distinct morphological and phenotypic profiles, including cellular morphology, gene expression, metabolism, motility, proliferation, metastatic potential, and sensitivity to medicines.

    What's precision medicine?

"Precision medicine refers to the use of information about the genes, proteins, and other features of a person’s cancer to diagnose or treat their disease."

——National Cancer Institute

Precision medicine (PM) is a medical model that proposes the customization of healthcare, with medical decisions, practices, and/or products being tailored to the individual patient.

    Goal of the Precision Medicine

In his 2015 State of the Union address, U.S. President Barack Obama stated his intention to fund a United States national "precision medicine initiative". A short-term goal of the Precision Medicine Initiative is to expand cancer genomics to develop better prevention and treatment methods. In the long-term, the Precision Medicine Initiative aims to build a comprehensive scientific knowledge base by creating a national network of scientists.

According to past statistics, the response rate of oncology drugs is only 20%, ranking last among all therapeutic areas. About 20% of cancer patients have a response, while the remainder gained a negligible survival benefit and experienced clinically significant side effects.

After decades of research, we are poised to enter a new era of medical practice where detailed genetic and other molecular information about a patient's cancer is routinely used to deploy effective, patient-specific remedies to treat each patient differently. We are about to enter the era of precision medicine.

Through DNA sequencing and analysis of each patient's tumors, we find genetic alterations associated with specific cancers. Understanding the genetic changes that are in cancer cells can lead to more effective treatment strategies that are tailored to the genetic profile of each patient's cancer.

    What's hereditary cancer?

We don't know the cause of most cancer, but experts believe that about 10% of most cancer types are due to inherited gene changes. Cancer that is not due to inherited gene changes is called “sporadic cancer.” It is believed that most—perhaps 90%—of all cancers are sporadic.Sporadic cancers are believed to arise from gene damage acquired from environmental exposures, dietary factors, hormones, normal aging, and other influences. Most acquired gene changes are not shared among relatives and are not passed on to children.

Hereditary cancers occur when a person is born with mutations in a damage-controlling gene which normally protects against cancer. In the majority of these cases, the changes were inherited from the mother or father. People with an inherited gene change have a 50% chance of passing the mutation to each of their children. Other blood relatives may share these same gene changes.

Sporadic cancer and hereditary cancer differ in several ways that may affect health care decisions:

   •   Individuals who have inherited a gene change may be at a higher risk for more than one type of cancer, but not everyone who is born with a gene mutation will develop cancer.

   •   Hereditary cancer often occur earlier than the sporadic form of the same cancer, so experts often recommend different screening, at a younger age for people with hereditary cancer in their family.

   •   For cancer survivors, this may affect cancer treatment options or follow-up care.

    Gene test available for cancer risk

"Hereditary cancer syndrome” describes an inherited gene mutation that increases the risk for one or more types of cancer. The main hereditary breast and ovarian cancer (HBOC) syndromes are caused by mutations in one of two genes: BRCA1 or BRCA2, which substantially increases the risk for breast and ovarian cancer, while slightly increasing the risk for other cancers.

According to NIH guidelines, there are more than 50 hereditary cancer syndromes. Genetic testing is available for some of the more common inherited cancer syndromes.

1. Hereditary breast cancer and ovarian cancer syndrome

Genes: BRCA1, BRCA2

Related cancer types: Female breast, ovarian, and other cancers, including prostate, pancreatic, and male breast cancer

2. Li-Fraumeni syndrome

Gene: TP53

Related cancer types: Breast cancer, soft tissue sarcoma, osteosarcoma (bone cancer), leukemia, brain tumors, adrenocortical carcinoma (cancer of the adrenal glands), and other cancers

3. Cowden syndrome (PTEN hamartoma tumor syndrome)

Gene: PTEN

Related cancer types: Breast, thyroid, endometrial (uterine lining), and other cancers

4. Lynch syndrome (hereditary nonpolyposis colorectal cancer)

Genes: MSH2, MLH1, MSH6, PMS2, EPCAM

Related cancer types: Colorectal, endometrial, ovarian, renal pelvis, pancreatic, small intestine, liver and biliary tract, stomach, brain, and breast cancers

5. Familial adenomatous polyposis

Gene: APC

Related cancer types: Colorectal cancer, multiple non-malignant colon polyps, and both non-cancerous (benign) and cancerous tumors in the small intestine, brain, stomach, bone, skin, and other tissues

6. Retinoblastoma

Gene: RB1

Related cancer types: Eye cancer (cancer of the retina), pinealoma (cancer of the pineal gland), osteosarcoma, melanoma, and soft tissue sarcoma

7. Multiple endocrine neoplasia type 1 (Wermer syndrome)

Gene: MEN1

Related cancer types: Eye cancer (cancer of the retina), pinealoma (cancer of the pineal gland), osteosarcoma, melanoma, and soft tissue sarcoma

8. Multiple endocrine neoplasia type 2

Gene: RET

Related cancer types: Medullary thyroid cancer and pheochromocytoma (benign adrenal gland tumor)

9. Von Hippel-Lindau syndrome

Gene: VHL

Related cancer types: Kidney cancer and multiple noncancerous tumors, including pheochromocytoma