Despite significant advancement in cancer research and management over past few decades, it still remains a leading cause of death worldwide. It is estimated that every year more than 14 million people are diagnosed with cancer translating to more than 8 million deaths worldwide. It is projected that by 2030 there could be 27 million people with cancer leading to more than 17 million cancer deaths each year. India had over 10 lakh new cancer cases and 6.8 lakh cancer deaths in the year 2012. More women (53%) than men (47%) developed new cancer, however; the mortality rate was more in men (52%) as compared to women (48%). While breast, cervix and colorectal cancer are top cancers in women ;lip/oral cavity, lung, stomach and colorectal cancer are top cancers in men in India.
Cancer happens due to the uncontrolled growth of the cells that are the basic building blocks of the body. Cancer occurs whenever a fault or a mutation happens in a gene. Mutations are caused by the natural processes in our cells, and by various other risk factors such as tobacco smoke, radiation exposure, ultraviolet radiation from the sun, diet, chemicals in our environment etc. Sometimes people inherit certain faulty genes from their parents which put them on an increased risk of developing cancer. Scientific advancements in molecular biology and genetics of cells have triggered the discovery of a novel approaches for an improved diagnosis as well as management of this disease.
The improved understanding of various genes responsible for causing certain cancers has triggered the discovery and development of targeted therapies. Targeted therapy is a general term that refers to a medication or drug that targets a specific pathway in the growth and development of a tumorsuch as a protein that allows the cancer cells to grow in a rapid or abnormal way. By attacking or blocking these important targets, the therapy helps to fight the tumor itself.Targeted cancer therapy acts like a magic bullet for hitting the cancer cells by taking cognizance of small differences between normal cells and cancer cells.
The various translational and targeted approaches for cancer management are being explored in the form of monoclonal antibodies, EGFR inhibitors, anti-angiogenesis, proteasome inhibitors, tyrosine kinase inhibitors, farnesyl transferase inhibitors, gene therapy and immunotherapy etc. The improved understanding of cancer genetics is also helping in predicting the response of therapies in certain cancer types.For example, patients with breast cancer with HER2 positive cells respond very well to newer drugs such as Trastuzumab and lapatinib. Similarly, in chronic myeloid leukemia (CML), drug that targets the BCR-ABL protein, such as imatinib, is often very effective. While some drugs does not work in certain gene mutations some work exceptionally well in specific gene mutations. For example, cetuximab and panitumumab does not help advanced colorectal cancers patients having mutations in the KRAS gene whereas erlotinib works better in non-small cell lung cancer patients whose cancer cells have a certain mutation in the EGFR gene.Although, targeted therapies can be used as the main treatment for some cancers, but in most cases they are used along with other treatments such as chemotherapy, surgery and/or radiation therapy. Targeted cancer therapies can be grouped on the basis of how they work or which part of a cell they target.
According to a report from American Cancer Society, the cancer death rate in US fell 23% in 21 years (1991 to 2012). The decline in cancer death rate is attributed to various factors such as early and better screening of the disease, availability of molecular diagnostic tools, availability of effective and targeted therapies and use of precision medicine for personalized treatment of individual cancer.
Targeted cancer therapies holds the promise of being more selective for cancer cells than normal cells, thus harming fewer normal cells, reducing side effects, and improving the quality of life. The encouraging result of targeted therapies is paving the way for a new era of personalized treatment approach in the management of cancer.
Written By: Dr. Sunil Gupta