Understanding The Common Cancer Terms

Contributed by: Dr Wong Siew Wei

When you or someone you know has been diagnosed with cancer, you may encounter complex medical terms that can be confusing. Whether you are a patient, caregiver or family member, understanding common cancer terms can empower you to take charge of your health and support your healthcare decision-making process.

Here are some common cancer terms1, explained:

Common terms used for cancer diagnosis


Cancer screening aims to help individuals detect precancerous conditions or cancer at an early stage before any symptoms appear.

Examples of cancer screening include: mammogram (for breast cancer), colonoscopy (for colon cancer), and Pap smear (for cervical cancer).


Scans that produce detailed pictures of areas inside the body. They may be used to help doctors diagnose cancer, plan treatment, assess treatment effectiveness, or observe disease progression over time.

Examples of imaging include: X-rays, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET).


Refers to the removal of cells or tissues for examination under a microscope. It is an important tool to diagnose many types of cancers.

Common types of biopsy procedures include:

  • Incisional biopsy – where only a sample of part of the lump is removed surgically
  • Excisional biopsy – where an entire suspected lump/tumour is removed surgically
  • Needle biopsy – where a small sample of tissue or fluid is removed with a needle, usually under live image guidance using scans

Cancer staging refers to a system that is used to describe the extent of the cancer in the body. Information is gathered using various modalities including blood tests, biopsy and imaging tests.

TNM staging is the most commonly used cancer staging system. Cancer stages are generally determined based on the local extent of the primary tumour (T), and the extent of cancer spread to adjacent lymph nodes (N) or other parts of the body (M). The stage of disease is used to plan the most appropriate treatment for the patient.

Common terms used to describe cancer


A solid mass of tissue that forms when abnormal clone(s) of cells grow and divide excessively. Tumours can be benign (non-cancerous) or malignant (cancerous).

Early-stage Cancer

A term used to describe cancer that is at the early stages of its growth, and has not spread to other parts of the body.

Advanced Cancer

Typically used to describe cancers that have spread (i.e. metastatic cancers) and are unlikely to be cured or controlled with treatment. While advanced cancers are unlikely to be cured, treatment may be given to shrink the cancer, slow the growth of cancer cells, help relieve symptoms and prolong life.

Locally advanced cancers refer to bulky cancers, typically with spread to surrounding lymph nodes or adjacent structures, but without spread to other distant organs. Some of these cancers may still be curable with multimodality treatment using effective drugs, radiation therapy and/or surgery.


The spread of cancer cells from its primary site to other parts of the body. When cancer cells metastasise, they break away from the primary site of the tumour, and travel through the blood or lymphatic system to form new colonies at other parts of the body.

Common terms used in cancer treatment

First-Line Treatment

When an oncologist talks about ‘line(s) of treatment’ in advanced cancer, they are referring to the order in which different treatments are given to a patient at different points of disease progression.

First-line treatment describes the initial, or first treatment recommended to be given for a particular disease. When first-line treatment does not work, second-line treatment is then given.


A procedure that aims to surgically remove the tumour from the body. It is the mainstay of treatment for many cancers.

Over the years, surgery has evolved to more precise procedures such as keyhole surgery—also known as laparoscopic surgery—where small incisions are made in the body to access the tumour; and robotic assisted surgery. Compared to open surgery, they offer patients faster recovery times without compromising on effectiveness.


Treatment that uses chemicals to kill fast-growing cancer cells in the body. It can be used with curative intent, or for symptom control and prolongation of life.

Radiation Therapy

The use of high-energy radiation such as X-rays, gamma rays and protons to kill cancer cells and shrink tumours.

The main types of radiation therapy are:

  • External-beam radiation therapy – where radiation comes from a machine outside the body
  • Brachytherapy – where radiation comes from radioactive material placed in the body
  • Systemic radiation therapy – where radioactive substances travel in the blood to tissues throughout the body
Neoadjuvant Therapy

Treatment given to shrink a tumour before first-line treatment is carried out. Previously, neoadjuvant therapy was primarily given when a tumour is too large to be operated on. Currently, it is also given to some cancers that are operable, to allow less extensive surgery to be carried out and improve long-term outcomes.

Neoadjuvant therapy should not be confused with adjuvant therapy, which refers to treatment given after first-line treatment to destroy any remaining cancer cells and lower the risk of the cancer coming back.

Common terms used to describe cancer outcomes


The likely outcome or course of a disease, or the chance of recovery or recurrence.

Disease-Free Survival (DFS)

Also called relapse-free survival (RFS), DFS refers to the length of time after first-line treatment that a patient survives without any signs and symptoms of cancer.


Cancer that has recurred or returned, usually after a period of time during which the cancer is in remission (a decrease in or disappearance of signs and symptoms of cancer). The cancer may return to the same place as the original primary tumour (local recurrence), to nearby tissues or lymph nodes (regional recurrence), or to other parts of the body (distant recurrence).

The definitions above are meant to be used as general references to help you better understand cancer health. As such, they are not fully comprehensive, and are not intended for use to diagnose or treat medical conditions. If you or someone you know require medical assistance, please seek help from a doctor.

1 NCI Dictionary of Cancer Terms

TAGS cancer diagnosis, cancer relapse, cancer screening, cancer ultrasound, chemotherapy, colonoscopy, mammogram, metastatic cancer, neoadjuvant therapy, pap smears, stage 4 cancer, tumours