Osteoporosis is a major side effect in the use of androgen deprivation therapy (ADT, hormone therapy) for prostate cancer. Men are urged to discuss any potential risks of osteoporosis and bone health in general with their physician. Primary risk factors include hormone therapy, lack of exercise, vitamin D deficiency, tobacco or alcohol use, thyroid problems, having a thin frame, previous fractures and bone metastases. Bone density measurements (not to be confused with bone scans for metastatic cancer) are generally obtained by either dual-energy X-ray absorptiometry (DEXA) scans or quantitative computed tomography (QCT) scans usually of the lumbar spine and hip. QCT is a technique that measures bone mineral density using a standard X-ray computed tomography scanner. QCT enables spine bone mineral density (BMD) measurements on patients with scoliosis, which cannot usually be measured using DXA scans. It is reported that for men, while the DEXA scan is the most commonly utilized, it seriously underestimates the degree of osteoporosis. QCT can avoid the artiﬁcially high BMD measurements that can confuse the results from DEXA scans in arthritic patients and patients who suffer from disc space narrowing or spinal degenerative diseases. Therefore, in the case of men with prostate cancer, some physicians recommend QCT over the more common DEXA scan. To enhance both muscle and bone density, weight-bearing exercise is essential. Several treatments are available for prostate cancer (pc) patients who have osteoporosis or bone metastases. These include: a) Zometa® (zolendronate), administered by i.v. drip monthly for pc patients with bone metastases; b) Xgeva® (denosumab), one injection monthly also for pc patients with bone metastases; c) Prolia® (denosumab), administered by injection every 6 months for men with osteoporosis or pc patients on hormonal therapy at high risk of fracture; and, d) Reclast® (zolendronate), administered by i.v. drip annually in men with osteoporosis. It is recommended that patients take calcium and vitamin D3 supplements and monitor them regularly by blood tests while taking any of the above-medications. Also a dental checkup is recommended before starting any of the above. It should also be noted that the greatest benefit from these agents is observed in the first year or two and it is possible to be on them too long when their risks begin to outweigh their benefits. As always, on-going thorough discussions with your oncologist or urologist regarding osteoporosis, bone health and prostate cancer is a necessity. Major portions of this article were summarized from the February issue of the Prostate Cancer Research Institute (PCRI) Insights as well as the following linked Wikipedia site.
About half of all men treated for prostate cancer will be prescribed hormone therapy, otherwise known as Androgen Deprivation Therapy (ADT) wherein testosterone levels are significantly reduced. Although ADT is not usually considered curative, it can keep prostate cancer in check for years and even decades. ADT is often initiated prior to radiation therapy to improve its efficacy. This use of ADT is called neo-adjuvant therapy. ADT is also used in the event of residual cancer after initial surgery or radiation therapy. Such use is referred to as adjuvant therapy. Systemic therapy is when ADT is used to treat cancer that has spread beyond the prostate gland. While ADT has obvious benefits, it also causes an array of side effects in addition to the well-known hot flushes. For example, the risks of osteoporosis, bone fracture, anemia, cardiovascular and kidney disease as well as diabetes and fatigue are increased. Also, weight is gained at the expense of muscle mass (sarcopenic obesity). There are also psychological effects of ADT as well. Recent controlled studies have indicated that ADT is notably associated with an increased risk of depression. There have also been several studies which suggest that ADT may impact mental cognitive functions involved in how one perceives, reasons, thinks and remembers. In addition, ADT can negatively affect a man’s interactions with the person he is normally closest to, such as a spouse or partner. This can also have repercussions on the latter’s health. In general, the psychological distress associated with cancer is greater on females than on males whether they are the patient or the partner. On a positive note, when it comes to dealing with physical or psychological side effects of ADT, physical exercise helps uniformly. It not only protects the heart, muscles and bones but it can improve mood and memory, reduce depression and fatigue and even improve sexual function. In fact, exercising together with a spouse or partner can help maintain intimacy and strengthen their spousal bond. Finally, one recent study noted that the survival benefit for prostate cancer patients in having a supportive spouse beats the benefits of chemotherapy. This entire article linked herein recently appeared in the February 2015 issue of the Prostate Cancer Research Institute (PCRI) Insights. The reader is highly encouraged to read and subscribe to the entire article, issue and periodical.
The Prostate Cancer Research Institute (PCRI) publishes a periodical entitled Insights which is available by e mail or regular mail. I strongly advise readers to subscribe electronically. The February issue discussed several very important topics including molecular imaging. After initial surgery or radiation prostate cancer treatment, 40% of patients will experience a PSA relapse. Knowing the location of the recurrence is important since recurrence at or near pelvic lymph nodes may be amenable to additional curative focal therapy. Standard imaging techniques such as technetium bone scan, CT scans and MRI are usually unable to see tiny recurrent tumors. However, PET scans which work by exploiting various aspects of cancer metabolism can often visualize and locate these small tumors. Acetate and choline represent two building blocks of cancer cell membrane synthesis. Therefore, if these areas of the cancer cell are made radioactive with carbon-11 (C-11) acetate or C-11 choline or fluorine-18 (F-18) radioactive isotopes, these areas can be observed on a body scan. The article’s author, Dr. Fabio Almeida, Director of the Arizona Molecular Imaging Center, provides data on 373 patients with PSA recurrence who were scanned with C-11 acetate PET scan. Cancer detection rates correlated with the patient’s PSA level. PSA levels of 0.2 – 0.4 ng/mL, led to 50% cancer detection rate; a PSA of 0.41-1.0 ng/mL led to a 77% detection rate; while a PSA level greater than 1.1 produced a detection rate of over 90%.
Other scanning methods discussed in the article include PET scanning using a radioactive gallium-68 labelled prostate specific membrane antigen (PSMA) agent. PSMA is a cell surface transmembrane glycoprotein that is over-expressed in prostate cancer cells. Another method uses a synthetic, non-metabolized amino acid analog labelled with radioactive fluorine-18 (anti-18F-FACBC) which accumulates in prostate cancer cells due to over-expression of multiple amino acid transport systems. PET scan results using this label appear to be comparable to C-11 acetate or C-11 choline scans especially when the PSA level is greater than 1.0 ng/mL. Very small bony lesions can be best detected by PET/CT scanning using sodium fluoride radiolabelled with fluorine-18 (F18-NaF) which is readily absorbed into the matrix of bone and has very high affinity for bone metastatses. F18-NaF provides higher sensitivity and specificity than bone scans based on technetium-bone imaging. In conclusion, while multi-parametric MRI is becoming the imaging study of choice for initial prostate cancer diagnosis and targeted biopsy, PET scans such as those discussed above may be complimentary especially in higher-risk patients to rule out the presence of local and distant sites of metastatic disease. The PCRI article concludes with a comparison of the above radiolabels pertaining to their production in a cyclotron, their urinary excretion, their half-lives and specificities. The author states that while C-11 acetate and C-11 choline offer several positive characteristics, their short half-life requires more dedicated equipment. Of the probes, F18-FACBC seems to come closest to having the optimal characteristics.