Prostate cancer is a complex disease that affects millions of men worldwide [1-3]. It is the second most common cancer in men after lung cancer, accounting for 7% of newly diagnosed cancer cases globally [1, 2]. Overall, prostate cancer is one of the most common solid malignancies. Each year, more than 1.2 million new cases are diagnosed globally, with prostate cancer-related deaths exceeding 350,000, making it one of the leading causes of cancer-related death in men [1, 2, 4, 5].

The prostate gland is a male reproductive accessory organ located beneath the bladder and surrounding urethra, and its main function is to maintain sperm viability [2, 6]. The cells in the prostate gland often give rise to tumors, most often in mid to late life [2, 7]. The risk of prostate cancer increases rapidly with age and more than 85% of newly diagnosed men are older than 60 years [1-3, 8]. Therefore, the incidence of prostate cancer is higher in countries with higher life expectancy, such as the US and the UK.

Prognosis varies greatly with age, ethnicity, genetic background and stage of progression [1-3]. At diagnosis, most prostate cancers are localized and asymptomatic. Clinical signs associated with prostate cancer include elevated protein levels of PSA on laboratory testing and an abnormal prostate finding on rectal examination. Among the few patients in whom prostate cancer is metastatic at the time of diagnosis, bone pain may be the prominent symptom, because bone is the predominant site of prostate cancer metastases [9]. Metastasis is the spread of cancer cells from the site where they first originated to another part of the body.

For some men, living with prostate cancer involves managing a customized treatment plan for a slow-growing and often indolent tumor. However, disease recurrence (exacerbation, relapse) after treatment can also be expected for many, which can be rapid, aggressive and in some cases unresponsive to standard treatment. Currently, there is no accurate method to predict aggressive from slow-growing tumors [2].

The prognosis for prostate cancer is highly variable and depends on tumor grade and stage at diagnosis. Today's early detection methods, such as PSA testing and digital rectal examination, enable diagnosis in most men at an early stage of the disease. Approximately 80% of men are diagnosed with localized disease entirely within the prostate gland, about 15% with locoregional metastases (local positive lymph nodes), and about 5% with distant metastases [2, 3]. Patients with localized disease generally have a favorable prognosis with 99% overall survival at 10 years and a low to intermediate risk of recurrence, provided the disease is detected and treated at an early stage [2].

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For men with newly diagnosed prostate cancer, the most important factors in choosing initial treatment include the extent of the disease, the stage of the disease and the molecular characteristics of the tumor, serum PSA level, potential complications with different treatment approaches, the patient's general medical condition, age and comorbidities, as well as individual preferences.

Treatment for the disease is based on risk stratification of patients provided by US guidelines [10] and in accordance with UK [11] and Norwegian guidelines [12]. The disease is categorized into clinically local very low-risk, low-risk, intermediate-risk and high-risk prostate cancer and clinically local advanced or very high-risk prostate cancer. For localized disease and very low to intermediate risk prostate cancer, treatment options include active surveillance, redundant prostatectomy (surgery to remove part or all of the prostate gland), brachytherapy (internal radiation therapy) or external beam radiation therapy.

For intermediate-risk prostate cancer with a more unfavorable histology (due to increased risk of disease recurrence), hormone therapy, also known as androgen deprivation therapy (ADT), is recommended as part of a combination treatment. The aim of this treatment is the reduction of male hormones in the body, called androgens, or to stop them from sustaining prostate cancer cell growth. Active surveillance is not indicated for patients with unfavorable disease at intermediate risk [13].

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For locally high-risk or locally advanced very high-risk prostate cancer, standard treatment includes radiation therapy (combination of external and internal radiation therapy) and long-term hormone therapy, or thorough prostatectomy [10]. Men whose disease worsens (recurrence) after prostatectomy are treated with salvage radiotherapy and/or hormone therapy for local recurrence, or with hormone therapy combined with chemotherapy or novel androgen signaling targeted agents for recurrence [2].

ADT is a common first-line option for men with advanced prostate cancer, but the majority of patients progress despite androgen (hormonal) deficiency, and the prostate cancer is then considered castration-resistant and incurable. For men with metastatic and non-metastatic castration-resistant prostate cancer, several active therapies have emerged. Current treatment options include androgen receptor-targeted agents, chemotherapy, radionuclides (radioactive elements) and the PARP inhibitor Olaparib which is a type of targeted cancer drug treatment [2].

Currently, research aims to advance the detection, treatment and outcomes of prostate cancer, including gaining in-depth knowledge of the fundamental biology of all stages of the disease.

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