BCG is a vaccine used to prevent tuberculosis (TB), though it is also an effective treatment for certain non-invasive bladder cancers. It is administered directly to the bladder (intravesical).

BCG is a type of immunotherapy drug that can make the bladder react, thus activating the immune system to get rid of the cancer cells.

• When is it used?

BCG helps keep the cancer from coming returning to the lining of the bladder and also reduced the risk of the cancer becoming invasive. It is generally given when there is a high risk of the cancer coming back and growing into the muscle of the bladder (invasive cancer).

This may happen in patients who have:

- Carcinoma in situ (CIS), which normally cannot be eliminated in its entirely through surgery.

- Ta and T1 cancers that are grade 3 (high grade).

- T1 cancers that are grade 2 and larger than 3 cm in width and when there are several tumors in the bladder.

At least two weeks must pass between surgery and administration of BCG. It is usually given weekly over a 6-week period; this is followed by a 6-week rest period and then another 1–3 weeks of treatment. If the treatment works well it may be repeated for 1–3 weeks every 6 months; this is known as maintenance therapy.

• How is it given?

The treatment is normally given on an outpatient basis. Patients are usually asked to limit the amount of fluids they take in before the treatment, as doing this increases the concentration of BCG in the bladder.

• Side effects

Because BCG goes directly to the bladder, most of the side effects have to do with this organ. The most common side effects are:

- frequent need to urinate

- pain when urinating

- blood in the urine

- flu-like symptoms such as fatigue, overall achiness, and high temperature

These side effects usually get better in a day or two; if not, contact your doctor. It is important to drink lots of fluids to help eliminate the drug from the bladder and relieve some of the side effects. Taking painkillers can also help.

The most common adverse effects may include fever, joint pain, and cough. If you have any of these symptoms or feel generally unwell, get in touch with your medical team.

- Protecting your partner

Men should wear a condom if they have sex within the first week after receiving treatment with BCG.

- Contraception

We do not know how BCG can affect the fetus, which is why it is not advisable to become pregnant and it is important to use an effective method of contraception during the treatment and for six weeks thereafter.