What is Capecitabine and how does it work?

Capecitabine is a type of medicine called cytotoxic antimetabolite. This is used for the treatment of;

  • Metastatic colorectal cancer
  • Advanced stomach cancer
  • Breast cancer

The active form of this medicine is converted inside cancer cells to 5-fluorouracil (5-FU). The conversion of Capecitabine to 5-FU is carried out by some compounds within the body that are called enzymes. The enzyme accountable for the final step is found mostly in tumor tissues. This means that higher concentrations of the active 5-FU are produced within the tumor tissues rather than in other healthy areas of the body. The medicine is said to be targeted against cancerous cells. Cancers form when cells within the body multiply uncontrollably and abnormally. These cells spread which destroy the nearby tissues. 5-FU works by stopping the cancer cells from multiplying. It does this by inhibiting the production of the cells’ genetic material which is RNA and DNA. Both RNA and DNA are needed for the growth and multiplication of cells. 5-FU causes a deficiency of DNA and RNA in the cancer cells. This causes the cells to grow in an unbalanced way that results in the death of the cells.

5-FU can also affect normal and healthy cells particularly those that multiply quickly. However, because the Capecitabine is mostly converted to 5-FU only in the cancer cells, it means that side effects on normal healthy cells are less with this medicine than with traditional non-targeted 5-FU given via a drip. The most important side effect is on the bone marrow where blood cells are made. 5-FU can cut the production of blood cells which leaves people susceptible to infection. Regular blood tests are therefore needed to monitor levels of blood cells.

Metastatic colorectal cancer

Cancer cells may break away from a tumor in the colon or rectum and spread to other parts of the body through the bloodstream or lymphatic system. These cells may settle and form new tumors on a different organ. Even though the cancer has spread to a new organ, it is still named after the part of the body where it originally started. So, colorectal cancer that spreads or metastasizes to the lungs, liver or any other organ is called metastatic colorectal cancer. The most common site of metastases for colon or rectal cancer is the liver. Colorectal cancer cells may also spread to the lungs, brain, bones, or spinal cord.

Advanced stomach cancer

This usually begins in the mucus-producing cells that line the stomach. This type of cancer is called adenocarcinoma. Signs and symptoms of stomach cancer may include:

  • Feeling bloated after eating
  • Fatigue
  • Feeling full after eating small amounts of food
  • Severe indigestion that is always present
  • Severe and persistent heartburn
  • Unexplained and persistent nausea
  • Stomach pain
  • Unintentional weight loss
  • Persistent vomiting

When an error happens in a cell’s DNA, the cancer begins. The change causes the cell to divide and grow at a quick rate and to continue living when a normal cell would die. The accumulating cancerous cells form a tumor that can invade nearby structures. The cancer cells can break off from the tumor to spread throughout the body.

Breast cancer

This forms in the cells of the breasts which can occur in both men and women. Signs and symptoms may include:

  • A breast lump or thickening that feels different from the Change in the size, shape or appearance of a breast
  • surrounding tissue
  • Redness or pitting of the skin over your breast like the skin of an orange
  • A newly inverted nipple
  • Changes to the skin over the breast
  • Crusting, peeling, scaling, or flaking of the pigmented area of skin surrounding the nipple or breast skin

Doctors know that breast cancer happens when some breast cells begin to grow abnormally. These cells divide more rapidly than healthy cells do and continue to accumulate, forming a lump or mass. Cells may spread through your breast to your lymph nodes or to other parts of your body. Researchers have identified hormonal, lifestyle and environmental factors that may increase your risk of breast cancer. It’s likely that breast cancer is caused by a complex interaction of your genetic makeup and your environment.

How to use Capecitabine?

Capecitabine is taken by mouth usually twice a day or as directed by your doctor. Each dose is taken within 30 minutes after eating a meal. The dose prescribed and the number of treatment cycles you will need depends on the type and stage of cancer that is being treated, what other treatments you are having, and how well you respond to the treatments. It is important to follow the instructions given by your doctor. You will be asked to take this medicine twice a day for 14 days and then have a 7 day break from treatment. This 21 day period is one treatment cycle. However, if you are taking this medicine in combination with other treatments you may be asked to take this medicine twice a day continuously without a break. Follow carefully the instructions given by your doctor.

If you forget a dose at your usual time, skip the missed dose and just take your next scheduled dose as normal. Do not take the missed dose at all and do not double your next dose. Instead, continue with your regular dosing schedule and let your doctor know you missed a dose.

Side Effects

  • Severe nausea or vomiting
  • Loss of appetite
  • Stomach pain or upset
  • Constipation
  • Weakness
  • Tiredness
  • Numbness or tingling in your hands or feet
  • Back, joint, muscle pain
  • Dizziness
  • Headache
  • Trouble sleeping
  • Skin rash
  • Skin darkening
  • Dry or itchy skin

Call your doctor right away if you have these side effects:

  • Blisters or ulcers in your mouth
  • Trouble swallowing
  • Eating much less than usual
  • Vomiting more than once in 24 hours
  • Severe skin infection (sore throat, fever, burning in your eyes, skin pain, swelling in your tongue or face)

Things to Remember

  • Capecitabine should be used with caution in people over 60 years of age, people with decreased kidney function, with disease affecting the brain or nervous system, and with diabetes mellitus.
  • This medication is not recommended for use in people with a history of severe and unexpected reactions of fluoropyrimidine therapy, people with very low numbers of platelets in their blood, and people with very low numbers of white blood cells in their blood.
  • Consult your doctor first before starting treatment with this drug.
  • Let your doctor know if you ever had an allergic reaction to this drug. Tell as well if you have any allergies.
  • Do not operate machinery or drive while having this medicine. This may make you dizzy.