Prostate cancer is now an important public health problem. It is the second most frequently diagnosed cancer in men today, being the 4th leading cause of cancer death in men in Western countries, including Portugal. Although there are no concrete figures for our country, we know that, in the USA alone, for example, 28900 men died of prostate cancer in 2003. In 2005, 230,110 men were diagnosed with prostate cancer in the same country, a number that will rise to 380,000 by 2025. The lifetime risk of a Western man being diagnosed with prostate cancer is 16.6%. In Europe, 247 men die every day due to this pathology. Studies show that the incidence of prostate cancer has been increasing in recent decades. The causes are unclear and, although more aggressive strategies for early diagnosis may, in part, explain this increase, other causes associated with diet, lifestyle, or the environment cannot be excluded.
The incidence of prostate cancer increases with age, meaning it is not a disease of young men. However, we have been witnessing the appearance of this neoplasm at increasingly earlier ages. Most guidelines still advise annual screening starting at age 50, or age 45 for high-risk groups, such as black individuals or those with first-degree relatives with a history of prostate cancer. However, the number of cases below the age of 50 is increasing, so many urologists advise a regular consultation from the age of 40.
We still do not know the causes of this type of cancer. Our knowledge of risk factors is incomplete. In addition to age and family history, other factors seem to be important. In fact, the risk of developing prostate cancer seems to vary from population to population, being much more frequent in western countries such as the USA, Canada, and Europe than, for example, in Asian countries. On the other hand, the risk is higher in black individuals.
Prostate cancer diagnosis
Prostate cancer usually develops without any symptoms, only manifesting itself in a very advanced (spread) stage, with no possibility of cure. Contrary to what most people believe, urinary symptoms rarely occur at an early stage. In fact, nowadays, 80% of cases are diagnosed by routine medical examinations performed on apparently healthy individuals, without any complaints. Hence the importance of early diagnosis, that is, at a stage of disease located in the prostate, still without symptoms, but curable. The diagnosis is suggested by altering one of the following tests: digital rectal examination, PSA (prostate specific antigen) blood test and transrectal prostate ultrasound. The digital rectal examination is a very easy and simple exam, which consists of digital prostatic palpation (with the finger), via the anal route, which can provide important information about prostatic volume, consistency and limits. Unfortunately, some men still delay going to the urologist for fear of this exam. PSA is a substance produced by the normal prostate, but whose blood values rise when there are prostate diseases, particularly in the case of prostate cancer. It is important to note that an elevation of PSA does not necessarily mean the existence of prostate cancer, although it is necessary to exclude it. PSA elevation occurs on average up to five years before any abnormality is detected on digital rectal examination. Today special types of PSA are used, such as free PSA or complexed PSA, which seek to increase specificity in the detection of prostate cancer, that is to say, they reduce the cases of false positives. Finally, transrectal prostate ultrasound, although not recommended by all urologists, offers important information, such as the existence of suspicious prostatic nodules or compromised gland boundaries. When any of these tests reveal changes that become suspicious, we must confirm the diagnosis of cancer by performing a prostate biopsy. It is a technique that consists in the collection of several prostate fragments, by ultrasound and transrectal route, which are then sent for histological study in order to verify the existence or not of cancer. It is a simple exam, quite well tolerated by the patient and that is performed in an outpatient setting without the need for any hospitalization with only local anesthesia.
Prostate cancer treatment
The treatment of prostate cancer essentially depends on two parameters: the age of the patient and the extent of the tumor. Older patients, that is, with a life expectancy of less than 10 years, are usually treated with hormone therapy alone, that is, with hormone suppression therapy, as prostate cancer is hormone-dependent, depending on stimulation by androgens such as testosterone. . This hormonal suppression can be achieved with surgical castration (removal of the testes) or chemical castration (with drugs that inhibit the production or action of testosterone). It is a type of treatment that works only temporarily (2 to 4 years), but which eventually allows patients of this age to die from their cancer and not from their cancer.
When patients have a life expectancy of more than 10 years, ie younger, we must offer the patient a treatment with curative intent, which is only possible if the disease is localized to the prostate. There are only three types of curative treatments for prostate cancer. The one considered most effective is radical prostatectomy, which consists of the surgical removal of the prostate and seminal vesicles. It allows a 10-year survival rate of over 90%, but with two important side effects: some degree of erectile dysfunction affecting 50 to 90% of patients and some urinary incontinence, usually transient, in the first few months, but which may be permanent between 3 to 10% of patients. As an alternative to surgery, some patients opt for external radiotherapy, a method with less impairment of sexual function and without repercussions on urinary continence, but with lower cure rates than surgery and not devoid of important and equally disabling side effects, such as radical rectitis. , radical cystitis, or alteration of intestinal transit. Recently, a third type of treatment has been introduced, prostatic brachytherapy, a form of interstitial radiotherapy, which consists of introducing radioactive seeds into the prostate under anesthesia. It is a method that has shown cure rates that are comparable to those of radical prostatectomy, in well-differentiated cancers, but with far fewer side effects, which is why it is increasingly preferred by patients. In the USA, where it has been around for about 15 years, it is chosen by more than half of patients.
Patients with metastatic disease (when the cancer has spread to other areas of the body) are treated with hormone therapy. Hormone therapy, although not curative, can lead to a long-term remission, allowing for an excellent quality of life. However, over time, prostate cancer can progress despite hormone therapy. It is not well known why this happens, but it progresses to a condition called hormone-resistant prostate cancer, in which about 70% of patients have bone metastases. The skeleton is the main target of metastasis of this type of cancer and when the disease reaches this stage there is no effective standard therapy and patients usually present severe and disabling complications such as intense bone pain, bone fractures or compression of neurological structures, which are associated with a decrease in survival. However, recent research in this area has made great strides, motivating renewed optimism. In recent years, some important new treatments have emerged, drawing new paths in the treatment of these hormone-resistant and metastatic patients. In addition to the substantial improvement in pain therapy, through the use of new analgesics, we now have two new drugs with proven results. The first is zoledronic acid, a class of bisphosphonates (a class of drugs that help rebuild and strengthen bone). This drug has shown significant effectiveness in reducing bone pain caused by metastases, as well as a decrease and a delay in the onset of bone complications from metastases such as fractures and the need for palliative radiotherapy. The introduction of zoledronic acid was a new and effective treatment of complications of bone metastases from prostate cancer. Studies are underway that point to the possibility of using this drug at an earlier stage in order to prevent the onset of bone metastases in patients at risk. The second drug recently introduced in the treatment of hormone-resistant patients is docetaxel, a type of chemotherapy that has been shown to significantly increase the survival of these patients, improving their quality of life and providing new hope for hormone-resistant patients.
One of the most fascinating areas in prostate cancer is chemoprevention, which consists of the regular administration of chemical substances, natural or synthetic, in order to prevent the onset and development of prostate cancer. Some natural products such as lycopenes (abundant in tomatoes), phytosteroids (abundant in soy), selenium, or vitamins A and D, have shown promising results. One of the most interesting studies in this area was the Prostate Cancer Prevention Trial, which showed a 25% reduction in the risk of developing prostate cancer in men who took 5 mg of finasteride daily, a drug that inhibits the activity of testosterone at the prostate level. , already used for many years in benign prostatic hyperplasia. Another study, the REDUCE study, seeks to show similar results with another drug: dutasteride. Results are expected this year. It is undoubtedly an area of future in oncology, which is only now taking its first steps.
In conclusion, although prostate cancer is very common, we currently have many therapeutic alternatives, even in the most advanced stages of the disease, which allow the patient with prostate cancer to look to the future with hope.