Targeted therapy does not beat about the bush. It aims straight for the centre of the problem. Coupled with clinical trials, in which promising new drugs are used, this therapy is offering new hope for significantly prolonged survival.

The average survival of a lung cancer patient with no treatment is six to eight months, and up to a year with regular chemotherapy. With targeted therapy, his survival can be even up to three years. Targeted therapy uses drugs that target cancer cells’ specific and unique features (mutations), while causing only minimal damage to normal cells. Regular chemotherapy, by contrast, targets fastdividing cells in general.

Dr Ravindran Kanesvaran, Consultant, Division of Medical Oncology, National Cancer Centre Singapore (NCCS), explained: “Cancer cells divide so rapidly that chemotherapy drugs are quite effective in targeting them. Unfortunately, normal cells that are fast-dividing, like hair cells and those in the mouth and digestive tract, also get affected.” 

That is why patients on chemotherapy experience side effects such as hair loss, sore mouth and nausea.

Targeted therapy: What it does 

Targeted therapy drugs only hit a cancer’s unique mutation, which is the factor causing its cells to grow and spread. The mutation may involve defects in the cells’ growth signals, their survival strategies to avoid cell death, or even their blood supply (read how targeted therapy works).

By blocking or switching off these defects or developments, a cancer can be brought under control, and the patient given an extended lease of life. “Patients may not be cured, but targeted therapy buys them a substantial amount of time. And there are relatively less side effects compared to chemotherapy because healthy cells are largely untouched. 

“The medication is usually taken orally, so a patient’s daily life isn’t disrupted, and overall, he enjoys better quality of life,” said Dr Ravindran.

Targeted therapy can be used when the mutation in a cancer has been identified. For example, the HER 2 mutation – a defect in the growth proteins in breast cells – is seen in about a quarter of breast cancer patients. It can be treated quite successfully by a targeted therapy drug, trastuzumab. 

But not all patients with the same type of cancer have cancer cells that exhibit the same mutations. The Cancer Genome Atlas (TCGA ) – a large international group – has analysed more than 20 tumour types to date, and found different mutations in each of these tumours.

Ref: N18