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Genitourinary Cancer – 10 – Prostate Cancer – Metastatic

Genitourinary Cancer  – 10

(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)
Question: Thank you Chiragbhai for several interesting points about treatment of localized prostate cancer. 1. Need for repeated prostate biopsies in active surveillance. 2. Need to add androgen deprivation therapy to Radiation therapy in higher risk cases. 3. Possible role of adding chemotherapy or abiraterone post radiotherapy in high risk cases, similar to postoperative treatment in several other cancers. 4. Some patients need radiotherapy after surgery, similar to postoperative radiotherapy in other high stage cancers. 5. Some patients have only biochemical relapse after surgery i.e. high PSA but no disease found on any scan. These patients need radiotherapy to prostate bed. 6. Robotic surgery reduces hospital stay by few days, but no change in cure rates. 7. PSMA PET scan is better than FDG PET scan for prostate cancer, to evaluate metastatic disease.
Now let us continue our discussion on metastatic or stage 4 prostate cancer. we discussed about diagnosis. How do you treat these patients? is it worth treating a stage 4 patient? Why put them through all the trouble and cost?
Answer: I am sure you remember our discussion on stage 4 cancer in so many cancer types. I believe I have convinced you enough that in most cases, treatment of stage 4 improves quality of life, and/or prolongs life even if not curative. And it is cost effective. Remember our discussion on breast, lung, several gastrointestinal cancers. Lymphomas can even be cured in majority of cases even in stage 4, same is true for testicular cancers.
Stage 4 prostate cancer treatment is probably the easiest and most cost effective in first few years post diagnosis. Main principle is that prostate cancer cells in large majority cases are hormone sensitive to start with. They are dependent on androgens. If you reduce androgen levels to very low, most cancer cells die. This gives dramatic relief of symptoms within days, and with generally normalization of PSA. This control lasts for about 2 years. This is true for majority, but not all patients.
Thereafter cancer cells develop ways to grow without androgens and become so called “hormone independent”. Treatment in this second phase, traditionally chemotherapy, has comparatively limited results and not always well tolerated in elderly population. New medicines have less side effects, but are much more expensive (although now better with Indian generics), and do not work well in aggressive cases. They are more suitable for a so called low aggressiveness metastatic disease, with low PSA and few or no symptoms.
In initial phase i.e. hormone sensitive phase, main treatment is Androgen Deprivation Therapy i.e. ADT. It is provided in form of:
1. Orchidectomy (also known as castration): bilateral testes removal reduces androgen levels by about 90%. It gives dramatic response in 48 hours in most cases. It is a minor surgery, with same day discharge, can be done in very weak patients too, and is very low cost. It results in permanent loss of testicular androgen production. It is used as first line option in vast majority of Indian patients.
2. Medical Castration: Use of medicines to suppress androgen production. These are GnRH analogues, given once every month or 3 months or 6 months as subcutaneous injection. Convenient, but not cost effective. In Indian context, orchidectomy can be done in cost of about 2 injections only. Main advantage is that unlike orchidectomy this is a temporary hormone suppression. This is definitely standard when someone needs hormone suppression for temporary periods, such as pre and post radiotherapy in high risk cases as we discussed earlier. However in metastatic disease, there is no medical advantage over orchidectomy. Metastatic disease requires lifelong androgen suppression, hence even if one chooses injections, it has to be given for the remaining life. Medical castration is used more widely in USA, Europe.
Surgical or medical castration is generally very well tolerated. However some patients may have significant symptoms, something like male menopause. There may be weakness, loss of sleep, depression, hot flashes, loss of appetite, impotence, gynecomastia. There may be mild to moderate anemia in some cases. Over long term some patients may develop osteoporosis, higher risk of cardiovascular disease. Later two are however uncommon, and do not require specific follow up or preventive measures in general.
July 15th 2018.

Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 079 26754001. Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com

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