Prostate cancer or prostate adenocarcinoma is the second most common type of cancer in men. It is estimated that a man of 9 will have this type of cancer throughout his life. 6 out of 10 cases are diagnosed in men over 65 years of age. Detected in the early stages, prostate cancer can be successfully treated, and at present, 90 percent of cases are diagnosed at onset. The prostate cancer treatment protocol may include patient monitoring, prostate removal, radiotherapy, but also other solutions. At present, patients are successfully treated within the oncology team of which the urologist, oncologist, imagist, surgeon, pathologist, radiation oncologist and nuclear medicine expert are members. In recent years, great progress has been made in the treatment of more serious cases of the disease. And these come from nuclear medicine, which offers modern diagnostic and treatment solutions such as those applied within ACIBADEM. Dr. Kemal Unal, one of the experts in nuclear medicine at ACIBADEM, explains in detail the solutions offered by the teams of doctors for the diagnosis and treatment of prostate cancer.
Dr. Kemal Unal: In our department, we use the imaging protocol with Ga 68-PSMA in patients diagnosed with prostate adenocarcinoma, to determine the stage of the disease. We can also use Ga 68-PSMA in patients with prostate adenocarcinoma who have metastases to evaluate the treatment response. Furthermore, if the patient has a new lesion, we use Ga 68-PSMA to reevaluate the disease stage. Ga 68-PSMA acts as follows: when we inject the patient with this radiotracer, it attaches to a receptor in the prostate adenocarcinoma membrane, then enters the cytoplasm. Thus, we manage to visualize prostate carcinoma cells. What we do is called molecular imaging with Ga 68-PSMA.
Dr. Kemal Unal: As I said, we use Ga 68-PSMA in imaging protocols. When we want to apply the treatments, we use Lutetium 177- PSMA because it has a higher energy than Ga-68. Absorption of Ga 68-PSMA is evaluated by means of scores, and prostate adenocarcinoma has a certain absorption rate that starts from the Gleason 6 score and reaches 10. The higher the score, the higher the absorption. Thus, we apply the diagnostic and treatment protocols to patients with scores greater than 7. If a patient has prostate adenocarcinoma and a high level of PSA in the blood, then we use Ga 68-PSMA to stage the disease. If metastases are suspected through ultrasound, MRI or scintigraphy examinations, we can apply the protocol with PSMA to establish the diagnosis.
Dr. Kemal Unal: For the diagnosis of prostate adenocarcinoma, the biopsy is performed initially. Then, we determine the Gleason score, to see if it is greater than 7. If the patient has a large tumor mass in the prostate gland or an increased level of PSA, we prefer to set the stage of the disease by Ga 68-PSMA imaging protocols. If the patient has a small tumor or low PSA level, we do not apply the protocol. It is recommended for patients with medium and high risk.
Dr. Kemal Unal: No special preparations are made before the test; the patient should not stop the medication. At the nuclear medicine department, we inject the radiotracer Ga 68-PSMA and the patient stays quiet for one hour. Then follows the investigation that is done with the help of PET-CT: the scan of the whole body takes 20-30 minutes. Then, if there are no artifacts (situations that occur if the patient has metal implants or as a result of breathing), we send the patient home. The only thing the patient has to do is avoid contact with pregnant women and children for a day, because there is a radioactive emission. Side effects of imaging protocols using Ga 68-PSMA do not exist. These may occur in the case of Lutetium-177 therapies, which involve high doses of radiation. Therefore, we carefully select patients based on blood test values and the status of liver and kidney functions (radiation therapy may worsen the condition of patients with kidney or liver problems). One of the side effects may be inflammation of the salivary glands. From my experience, we do not expect side effects if we choose patients carefully. After each Lutetium-177 cycle, we perform blood tests before entering the next cycle. We are very careful about this, as the side effects can affect between 3 and 5 percent of the patients, after the lutetium therapies.
Dr. Kemal Unal: If we talk about Lutetium-177 therapies, these are very important for metastatic patients because they are the only chance of treatment in some cases. If patients have metastases and are advised to do hormone therapy and chemotherapy, they may become resistant to these therapies (castration-resistant prostate adenocarcinoma) and then the only solution could be Lutetium -177 therapy. At present, it is known that if the tumor cells have a good absorption for Ga 68-PSMA, then they will also have for the Lutetium-177 therapy. The protocol is called diagnostic therapy, it is a new term in nuclear medicine. Lutetium-177 therapies are personalized and thus, we manage to treat all lesions at the same time. For example, if the patient has 100 metastases, no external radiation therapy may be applied to each lesion. But when we inject Lutetium-177 into the body, the tumors absorb it and thus, we can radiate more lesions in one cycle.
Dr. Kemal Unal: Our results are like those provided by statistics from the world’s largest nuclear medicine centers. We expect a 10% complete response to treatment. Most patients have a partial response to treatment, but this is a good thing because these patients have no other therapeutic options. Some have a stable response, which means that the disease stagnates, which is good for these patients. 20 or 30 percent of the patients are experiencing a progression of the disease under the treatment with Lutetium-177, but for them we also have solutions such as the actinium therapy that is already being done in Europe and Turkiye. Actinium is much more energetically active than Lutetium-177, it contains alpha particles, not beta like lutetium. It is an alternative for patients who do not respond to Lutetium-177, yet most respond to lutetium or have a stable situation. Also, in half of the patients taking Lutetium-177, the level of PSA in the blood is reduced.
Dr. Kemal Unal: There is no age limit for these therapies, but as you know, prostate adenocarcinoma occurs especially in old age, so most of our patients are around 60 years of age. There is no upper age limit for these therapies: if the patient has high life expectancy, we can apply the therapy at 90 years. A small group of patients develop prostate adenocarcinoma at a younger age, but nuclear medicine therapies are not the primary ones in prostate adenocarcinoma. So, these patients do chemotherapy or hormone therapy first. If patients develop resistance to these therapies, we switch to Lutetium-177. But it is possible that it may take some years before the Lutetium-177 treatment, so our patients are usually elderly.
Dr. Kemal Unal: The number of our patients increases every week. We started with a few patients a month, now we have a few a week. I think that their number will continue to increase because with the increase of life expectancy the number of patients with prostate adenocarcinoma will increase as well. The percentage of prostate carcinoma in total cancers is constantly increasing as a result of increased life expectancy. We look forward to the results of ongoing studies worldwide and we think they will be good. As soon as we find out the results, it will be much easier for doctors to recommend these treatments. With us, patients are referred by oncologists and urologists, so the results of the studies will stimulate them to guide patients to nuclear medicine therapies as well. In the future, we expect to use more high-energy particles, in addition to Lutetium-177, so the efficacy of the therapies could be improved. We already use actinium in patients with lutetiumresistance, actinium from which we expect even better results.
Dr. Kemal Unal: Prostate adenocarcinoma occurs especially in older age, but there is no data that these therapies would give permanent infertility. Radiopharmaceuticals are concentrated in carcinoma cells and some around, and do not affect distant tissues. Basically, by these methods, the cells are selectively irradiated, and the tissues are protected much better than in the case of external radiotherapy. Radiation is much better located.