Treating advanced prostate cancer: raising the options
Treating advanced stage prostate cancer is now possible, with better outcomesworld Updated: Apr 20, 2017 15:25 IST
New Delhi: Everywhere in the world, men over the age of 55 should be getting themselves checked early for prostate cancer. Otherwise, those who forego early testing might find themselves on the wrong side of the disease: in it’s advanced stages.
When detected early on, prostate cancer is often found localized – only in the prostate gland and its close surroundings. Active surveillance (watchful waiting) and prostate surgery are the standard of care treatments for early stage cancer and have generally optimistic outcomes.
Alternatively, men who are diagnosed at a late stage may be found to have locally advanced cancer or metastatic disease where the cancer has spread throughout the body – the bones and other organs respectively. At these late stages, the chance for “curing” the patient no longer exists.
However, other treatment options that slow the growth of cancer are available and many new approaches are currently underway.
To tackle advanced cancer, doctors first turn to hormone therapy, called Androgen Deprivation Therapy (ADT).
Hormone therapy is a widely used treatment in India, since the rate of advanced cancer is higher than in other parts of the world. ADT works either by preventing the body from stimulating testosterone-production (the male hormone) or by blocking the effects of testosterone itself.
Through a series of injections, the testosterone gradually decreases to near zero levels. Because cells in the prostate, including the cancerous ones, need testosterone to grow, the ADT treatment halts their lifecycle.
Unfortunately, hormone therapy won’t work effectively for many patients. Over time, the cancer cells develop what is called, “resistance,” and learn how to overcome the effects of ADT.
A new and emerging area of research is focusing on genomic technology that can tell doctors which patients are likely to develop resistance. The recent discovery of “androgen splice variants” has allowed researchers to figure out just who will benefit from hormone therapy and who will not.
Patients with hormone-resistant cancer can get started on chemotherapy right away, and the most commonly used chemotherapy drug is Docetaxel. Commonly known by its generic name, the drug is also sold under various brand names in India.
Given intravenously, the drug works by disrupting the cells’ growth cycle and preventing the cancer from spreading. Recent studies have focused on how Docetaxel can be used in combination with other therapies.
However, like other chemotherapy drugs, Docetaxel has many unsavory side effects that can seriously decrease a patient’s quality of life. That’s why researchers have been searching for a new treatment option that will kill the cancer cells as effectively with a lesser negative impact on the lives of prostate cancer patients.
A promising and exciting new area of research at the moment is immunotherapy: Harnessing the body’s
own immune system to fight cancer. Immunotherapy is the body’s own system of defense. Imagine that the body had its own cellular line of defense, say, the guardians of our organ systems. If we think about the body’s “T-cells,” as the guardians, the cancerous cells would most certainly be the bad guys.
When cancer invades the body, it learns to escape the surveillance of the guardians and stealthily grow in numbers. The aim of immunotherapy is to enhance the ability of the immune T-cells to find and kill the cancer cells by giving them the right tools.
Researchers in this field are focused on two very promising types of immunotherapy: vaccine-based and checkpoint inhibitors. Vaccine-based immunotherapies being used in prostate cancer treatment are unlike common vaccines, such as chicken-pox or flu shots. These vaccines are custom-made for each individual patient.
The immune cells are removed, genetically engineered to target cancer cells, and then reinfused back into the patient’s body or blood stream. These newly energized and trained immune cells track down and kill the prostate cancer cells.
Checkpoint inhibitors can also promote an effective anti-cancer immune response and are widely used to treat many other types of cancers. In a normal body, the immune T-cells known when to attack and when to stop. Like borders or walls, the body has “check-points” beyond which T-cells cannot act. The cancer cells learn to create such checkpoints so as to escape the attack from the immune T-cells.
If one can remove these check-points or “inhibit” them, the T-cells become capable of detecting and killing the cancer cells. Checkpoint inhibitors – as the name might suggest – prevent these checkpoints from being realized and allow the T-cells to keep fighting the cancer.
Currently, the only FDA approved immunotherapy in the United States is Sipuleucel-T, a vaccine-based treatment. As with Docetaxel, scientists are trying to understand when and how Sipuleucel-T can be most effective, whether it be alone or in combination with other treatments.
Many hospitals and research laboratories around the world are working on finding new immunotherapeutic and chemotherapeutic drugs. Since immunotherapy is thought to be most effective in early-stage cancers, researchers are also testing strategies to safely treat patients earlier on with less side-effects.