Case Reports: A Roundtable Discussion

CASE REPORT 1:

A patient with lumbar pain

· Dr. Porter: A 61-year-old gentleman is diagnosed with prostate cancer and undergoes a radical prostatectomy and lymph node dissection in 1983. Six years later, he presents with worsening pain in the lumbosacral spine and a PSA of 120. Therapeutic choices include: Hormonal manipulation; hormonal manipulation with radiotherapy to the lumbar cervical spine; isotope therapy; hemibody irradiation; or chemotherapy. How would you manage this patient?

Approximately 25% of our audience here would choose hormonal therapy and 75% would use both hormonal therapy and radiation therapy to the spine. Dr. Stone, what's your opinion?

· Dr. Stone: This patient has an excellent chance of responding completely to hormonal therapy. His presentation implies that he may fit into the category of minimal disease, with metastasis limited to the axial spine. Since these patients respond well to complete hormonal therapy, I would reserve radiation therapy for a relapse after hormonal therapy fails.

· Dr. Poulter: Hormonal therapy would be the obvious choice. The use of radiation therapy would depend on a number of factors, including the severity of pain, the risk of fracture or spinal cord compression, and the rapidity of the response to hormonal manipulation. PSA could be used to assess therapeutic effectiveness. My choice would be to start with one therapy because, when treating pain at a single site with two therapies, you do not know which one is providing the response.

· Dr. Logothetis: I would use hormonal therapy alone.

CASE REPORT 2:

A patient with spinal cord compression

· Dr. Porter: A patient is referred to you after having received 4 mCi of Sr-89 approximately 5 weeks ago. He now has signs of spinal cord compression at level T10. There are four treatment choices: Local field radiotherapy of 3,000 cGy in 10 fractions; neurosurgery; readminister Sr-89; or chemotherapy. How would you manager this patient?

Responses from our audience indicate that approximately 75% would treat with local field radiation therapy to the area causing the cord compression and 25% would refer the patient to neurosurgery. This case addresses the concern of an additive toxicity from Sr-89 in the spinal cord and external beam radiation . A frequently asked question is--How does one account for the dose of Sr-89 previously administered? Dr. McGowan, what would you recommend in this case?

· Dr. McGowan: I would treat with external beam radiation. I am not concerned about an additive toxicity with Sr-89 in the spinal cord, since the isotope is absorbed mainly in bone, with minimal dosage delivered to the spinal cord. Neurosurgical intervention could also be considered, however, our community of neurosurgeons are very reluctant to operate on a patient with spinal cord compression from prostate cancer.

· Dr. Porter: I agree that there are no additive effects with Sr-89 and external beam radiation, since Sr-89 is a pure beta emitter. In fact, the TransCanadian study reported no increase in additive complications from treating spinal cord compressions with local field radiation followed by Sr-89 treatment.

· Dr. McGowan: I would like to add that I have actually seen several patients develop a spinal cord compression after receiving Sr-89. However, it has usually occurred within a week to 10 days post-treatment, as opposed to the 5-week interval described in this case.

CASE REPORT 3:

What next for this man who failed leuprolide and flutamide(Drug information on flutamide)?

· Dr. Porter: A patient with D2 metastatic prostate cancer is treated with total androgen blockade consisting of leuprolide (Lupron) and flutamide (Eulexin). After 2 years on this therapy, he relapses and complains of pain that he describes as "fleeting." His bone scan is positive and his PSA has risen. Treatment choices include: Isotope therapy; hemibody radiotherapy; local field radiotherapy to bone-scan-positive areas; or chemotherapy using estramustine(Drug information on estramustine) (Emcyt) and VP-16 (etoposide, VePesid).

The majority of attendees in our audience chose isotope therapy.

· Dr. Logothetis: These patients require discussion in choosing the appropriate treatment regimen. If you have an 80-year-old gentleman, there is typically no interest in the inconvenience associated with investigational therapy. Therefore, strontium would be the appropriate choice when pain palliation is the main therapeutic goal. Alternatively, a younger patient or one who would prefer to explore all available options, would be a candidate for investigational therapy. Once these patients understand that these treatment options are unproven, the choices of estramustine, VP-16, or various combinations can be considered. I know of no proven advantages among them at this time.

I have a note on one of the question cards submitted by the attendees inquiring about angiogenesis inhibitors, which we are studying. One such drug, fumagillin, is currently being tested clinically for the treatment of prostatic carcinoma.

CASE REPORT 4:

May this man be cremated?

· Dr. Porter: An 84-year-old man was treated with 4 mCi of Sr-89 5 months ago. His disease progressed and he died. His family wishes to have him cremated. As the radiation oncologist, should you advise that the body be stored for two half-lives prior to cremation and should you advise the crematory about the Sr-89, or is that not necessary? Is radiation emission from the body not a concern?

There are few rules governing the cremation of a body containing a beta emitting substance. One study, by the International Association of Physicists in Medicine, addressed safety rules concerning Sr-89. This association is not a legal body in the United States. Nonetheless, they recommend that a body could be cremated with a dose of 400 MBq of Sr-89 and buried with a dose of 1000 MBq (divide by 37 to convert MBq to mCi). Since 400 MBq is well above the dosage currently used, a patient could be cremated even if he died the same day the Sr-89 was administered. The cremating facility should, of course, be informed. The Nuclear Regulatory Commission met with us recently and is debating the standards of dose responsibilities for Sr-89.

CASE REPORT 5:

Pain in the lumbar spine

· Dr. Porter: A patient with well-controlled primary lung cancer requires palliative radiotherapy for a painful metastasis in the lumbar spine. How should this patient be treated in terms of dose fractionation? On the basis of the data that Colin Poulter presented (see page 19), would you use: 800 cGy in a single local field fraction; 2,000 cGy in five fractions; 3,000 cGy in 10 fractions; or 4,000 cGy in 20 fractions.

Responses from our attendees indicate that 3,000 cGy in 10 fractions is considered standard in North America. Colin, what are your thoughts on dose fractionation?

· Dr. Poulter: Our standard treatment dosage is 3,000 cGy in 10 fractions. However, since numerous factors are considered in dose determination, we frequently deviate from the standard protocol. Some patients, for example, would receive a single dose of 800 cGy.

· Dr. McGowan: My standard treatment regimen is 2,000 cGy in 5 fractions or 1,000 cGy in a single fraction. The dose is decreased to 800 cGy in a single fraction for rib metastases. The single treatment patients are often those who must travel long distances. In Canada, some patients have to travel 300 or 400 miles for treatment, prompting most Canadian clinicians to use shorter fractionations for practical reasons.