Prostate cancer screening is an attempt to find unsuspected cancers. Initial screens may lead to more invasive follow-up tests such as a biopsy. Options include the digital rectal exam (DRE) and the prostate-specific antigen (PSA) blood test. Such screening is controversial and, in some people, may lead to unnecessary disruption and possibly harmful consequences. Routine screening with either a DRE or PSA is not supported by the evidence as there is no mortality benefit from screening.

The United States Preventive Services Task Force (USPSTF) recommends against the PSA test for prostate cancer screening in healthy men regardless of age. They concluded that the potential benefit of testing does not outweigh the expected harms. The Centers for Disease Control and Prevention shared that conclusion. The American Society of Clinical Oncology and the American College of Physicians discourages screening for those who are expected to live less than ten to fifteen years, while in those with a greater life expectancy a decision should be made by the person in question based on the potential risks and benefits. In general, they concluded, "it is uncertain whether the benefits associated with PSA testing for prostate cancer screening are worth the harms associated with screening and subsequent unnecessary treatment." American Urological Association (AUA 2013) guidelines call for weighing the benefits of preventing prostate cancer mortality in 1 man for every 1,000 men screened over a ten-year period against the known harms associated with diagnostic tests and treatment. The AUA recommends screening decisions in those 55 to 69 be based on shared decision making, and that if screening is performed it should occur no more often than every two years.

In those who are being regularly screened, 5-alpha-reductase inhibitor (finasteride and dutasteride) reduce the overall risk of being diagnosed with prostate cancer; however, there is insufficient data to determine if they have an effect on the risk of death and may increase the chance of more serious cases.

The U.S. Preventive Services Task Force (USPSTF) issues recommendations for various cancers:

- Strongly recommends cervical cancer screening in women who are sexually active and have a cervix at least until the age of 65.

- Recommend that Americans be screened for colorectal cancer via fecal occult blood testing, sigmoidoscopy, or colonoscopy starting at age 50 until age 75.

- Evidence is insufficient to recommend for or against screening for skin cancer, oral cancer, lung cancer, or prostate cancer in men under 75.

- Routine screening is not recommended for bladder cancer, testicular cancer, ovarian cancer, pancreatic cancer, or prostate cancer.

- Recommends mammography for breast cancer screening every two years from ages 50–74, but does not recommend either breast self-examination or clinical breast examination. A 2013 Cochrane review concluded that breast cancer screening by mammography had no effect in reducing mortality because of overdiagnosis and overtreatment.

Screens for gastric cancer using photofluorography due to the high incidence there.

As of 2010 there is insufficient evidence to determine if screening for bladder cancer in people without symptoms is effective or not.

In 2013 a preliminary, small study of 98 samples of urine, all from men—24 who had cancer, and 74 with bladder-related problems but no cancer yet used a gas chromatograph to successfully examine the vapor from heated urine samples to identify cancer.

Cystoscopy, a procedure in which a flexible tube bearing a camera and various instruments is introduced into the bladder through the urethra allows diagnosis and by biopsying suspicious lesions.

The gold standard for diagnosing bladder cancer is biopsy obtained during cystoscopy. Urine cytology can be obtained in voided urine or at the time of the cystoscopy ("bladder washing"). Cytology is not very sensitive (a negative result cannot reliably exclude bladder cancer). There are newer non-invasive urine bound markers available as aids in the diagnosis of bladder cancer, including human complement factor H-related protein, high-molecular-weight carcinoembryonic antigen, and nuclear matrix protein 22 (NMP22). NMP22 is also available as a prescription home test. Other non-invasive urine based tests include the CertNDx Bladder Cancer Assay, which combines FGFR3 mutation detection with protein and DNA methylation markers to detect cancers across stage and grade, UroVysion, and Cxbladder.

The diagnosis of bladder cancer can also be done with a Hexvix/Cysview guided fluorescence cystoscopy (blue light cystoscopy, Photodynamic diagnosis), as an adjunct to conventional white-light cystoscopy. This procedure improves the detection of bladder cancer and reduces the rate of early tumor recurrence, compared with white light cystoscopy alone. Cysview cystoscopy detects more cancer and reduces recurrence. Cysview is marketed in Europe under the brand name Hexvix

However, visual detection in any form listed above, is not sufficient for establishing pathological classification, cell type or the stage of the present tumor. A so-called cold cup biopsy during an ordinary cystoscopy (rigid or flexible) will not be sufficient for pathological staging either. Hence, a visual detection needs to be followed by transurethral surgery. The procedure is called transurethral resection of bladder tumor (TURBT). Further, bimanual examination should be carried out before and after the TURBT to assess whether there is a palpable mass or if the tumour is fixed ("tethered") to the pelvic wall. The pathological classification obtained by the TURBT-procedure, is of fundamental importance for making the appropriate choice of ensuing treatment and/or follow-up routines.

HGPIN in isolation does not require treatment. In prostate biopsies it is not predictive of prostate cancer in one year if the prostate was well-sampled, i.e. if there were 8 or more cores.

The exact timing of repeat biopsies remains an area of controversy, as the time required for, and probability of HGPIN transformations to prostate cancer are not well understood.

HGPIN is diagnosed from tissue by a pathologist, which may come from:

- a needle biopsy taken via the rectum and,

- surgical removal of prostate tissue:

- transurethral resection of the prostate - removal of extra prostate tissue to improve urination (a treatment for benign prostatic hyperplasia),

- radical prostatectomy - complete removal of prostate and seminal vesicles (a treatment for prostate cancer).

Blood tests for prostate specific antigen (PSA), digital rectal examination, ultrasound scanning of the prostate via the rectum, fine needle aspiration or medical imaging studies (such as magnetic resonance imaging) are "not" useful for diagnosing HGPIN.

Prognosis can range considerably for patients, depending where on the scale they have been staged. Generally speaking, the earlier the cancer is diagnosed, the better the prognosis. The overall 5-year survival rate for all stages of penile cancer is about 50%.

Antibodies may be used to determine the expression of protein markers on the surface of cancer cells. Often the expression of these antigens is similar to the tissue that the cancer grew from, so immunohistochemical testing sometimes helps to identify the source of the cancer. Individual tests often do not provide definitive answers, but sometimes patterns may be observed, suggesting a particular site of origin (e.g. lung, colon, etc.). Immunohistochemical testing suggests a single source of cancer origin in about one in four cases of CUP. However, there is a lack of definitive research data showing that treatment guided by information from immunohistochemical testing improves outcomes or long-term prognosis.

Most people with cancer of unknown primary origin have widely disseminated and incurable disease, although a few can be cured through treatment. With treatment, typical survival with CUP ranges from 6 to 16 months. Survival rates are lower in cases with visceral metastatic disease, ranging from 6 to 9 months. Survival rates are higher when the cancer is more limited to lymph nodes, pleura, or peritoneal metastasis, which ranges from 14 to 16 months. Long-term prognosis is somewhat better if a particular source of cancer is strongly suggested by clinical evidence.

Many imaging modalities are used to aid in the diagnosis of primary liver cancer. For HCC these include sonography (ultrasound), computed tomography (CT) and magnetic resonance imaging (MRI). When imaging the liver with ultrasound, a mass greater than 2 cm has more than 95% chance of being HCC. The majority of cholangiocarcimas occur in the hilar region of the liver, and often present as bile duct obstruction. If the cause of obstruction is suspected to be malignant, endoscopic retrograde cholangiopancreatography (ERCP), ultrasound, CT, MRI and magnetic resonance cholangiopancreatography (MRCP) are used.

Tumor markers, chemicals sometimes found in the blood of people with cancer, can be helpful in diagnosing and monitoring the course of liver cancers. High levels of alpha-fetoprotein (AFP) in the blood can be found in many cases of HCC and intrahepatic cholangiocarcinoma. Cholangiocarcinoma can be detected with these commonly used tumor markers: carbohydrate antigen 19-9 (CA 19-9), carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125). These tumour markers are found in primary liver cancers, as well as in other cancers and certain other disorders.

There are several treatment options for penile cancer, depending on staging. They include surgery, radiation therapy, chemotherapy, and biological therapy. The most common treatment is one of five types of surgery:

- Wide local excision—the tumor and some surrounding healthy tissue are removed

- Microsurgery—surgery performed with a microscope is used to remove the tumor and as little healthy tissue as possible

- Laser surgery—laser light is used to burn or cut away cancerous cells

- Circumcision—cancerous foreskin is removed

- Amputation (penectomy)—a partial or total removal of the penis, and possibly the associated lymph nodes.

Radiation therapy is usually used adjuvantly with surgery to reduce the risk of recurrence. With earlier stages of penile cancer, a combination of topical chemotherapy and less invasive surgery may be used. More advanced stages of penile cancer usually require a combination of surgery, radiation and chemotherapy.

In addition to all the above, treatment of the underlying disease like brucellosis, is important to limit disease recurrence.

The clinical diagnosis of BPH is based on a history of LUTS (lower urinary tract symptoms), a digital rectal exam, and exclusion of other causes of similar signs and symptoms. The degree of LUTS does not necessarily correspond to the size of the prostate. An enlarged prostate gland on rectal examination that is symmetric and smooth supports a diagnosis of BPH. However, if the prostate gland feels asymmetrical, firm, or nodular, this raises concern for prostate cancer.

Urinalysis is typically performed when LUTS are present and BPH is suspected to evaluate for signs of a urinary tract infection, glucose in the urine (suggestive of diabetes), or protein in the urine (suggestive of kidney disease). Bloodwork including kidney function tests and prostate specific antigen (PSA) are often ordered to evaluate for kidney damage and prostate cancer, respectively. However, checking blood PSA levels for prostate cancer screening is controversial and not necessarily indicated in every evaluation for BPH. Benign prostatic hyperplasia and prostate cancer are both capable of increasing blood PSA levels and PSA elevation is unable to differentiate these two conditions well. If PSA levels are checked and are high, then further investigation is warranted. Measures including PSA density, free PSA, rectal examination, and transrectal ultrasonography may be helpful in determining whether a PSA increase is due to BPH or prostate cancer. Ultrasound examination of the testes, prostate, and kidneys is often performed, again to rule out cancer and hydronephrosis.

Validated questionnaires such as the American Urological Association Symptom Index (AUA-SI), the International Prostate Symptom Score (I-PSS), and more recently the UWIN score (urgency, weak stream, incomplete emptying, and nocturia) are useful aids to making the diagnosis of BPH and quantifying the severity of symptoms.

"DCIS patients and control subjects did not differ with respect to oral contraceptive use, hormone replacement therapy, alcohol consumption or smoking history, or breast self-examination. Associations for LCIS were similar."

Prevention of cancers can be separated into primary, secondary, and tertiary prevention. Primary prevention preemptively reduces exposure to a risk factor for liver cancer. One of the most successful primary liver cancer preventions is vaccination against hepatitis B. Vaccination against the hepatitis C virus is currently unavailable. Other forms of primary prevention are aimed at limiting transmission of these viruses by promoting safe injection practices, screening blood donation products, and screening high-risk asymptomatic individuals. Aflatoxin exposure can be avoided by post-harvest intervention to discourage mold, which has been effective in west Africa. Reducing alcohol abuse, obesity, and diabetes would also reduce rates of liver cancer. Diet control in hemochromatosis could decrease the risk of iron overload, decreasing the risk of cancer.

Secondary prevention includes both cure of the agent involved in the formation of cancer (carcinogenesis) and the prevention of carcinogenesis if this is not possible. Cure of virus-infected individuals is not possible, but treatment with antiviral drugs such as interferon can decrease the risk of liver cancer. Chlorophyllin may have potential in reducing the effects of aflatoxin.

Tertiary prevention includes treatments to prevent the recurrence of liver cancer. These include the use of chemotherapy drugs and antiviral drugs.

A systematic review found evidence that light drinking may decrease the risk of nasopharyngeal carcinoma whereas high intake of alcohol may increase the risk.

A CT scan can detect bone metastases before becoming symptomatic in patients diagnosed with tumors with risk of spread to the bones. Even sclerotic bone metastases are generally less radiodense than enostoses, and it has been suggested that bone metastasis should be the favored diagnosis between the two for bone lesions lower than a cutoff of 1060 Hounsfield units (HU).

Voiding position when urinating may influence urodynamic parameters (urinary flow rate, voiding time, and post-void residual volume). A meta-analysis found no differences between the standing and sitting positions for healthy males, but that, for elderly males with lower urinary tract symptoms, voiding in the sitting position:

- the post void residual volume was decreased

- the maximum urinary flow was increased, comparable with pharmacological intervention

- the voiding time was decreased

This urodynamic profile is associated with a lower risk of urologic complications, such as cystitis and bladder stones.

Genetic testing for mutations in DNA mismatch repair genes is expensive and time-consuming, so researchers have proposed techniques for identifying cancer patients who are most likely to be HNPCC carriers as ideal candidates for genetic testing. The Amsterdam Criteria (see below) are useful, but do not identify up to 30% of potential Lynch syndrome carriers. In colon cancer patients, pathologists can measure microsatellite instability in colon tumor specimens, which is a surrogate marker for DNA mismatch repair gene dysfunction. If there is microsatellite instability identified, there is a higher likelihood for a Lynch syndrome diagnosis. Recently, researchers combined microsatellite instability (MSI) profiling and immunohistochemistry testing for DNA mismatch repair gene expression and identified an extra 32% of Lynch syndrome carriers who would have been missed on MSI profiling alone. Currently, this combined immunohistochemistry and MSI profiling strategy is the most advanced way of identifying candidates for genetic testing for the Lynch syndrome.

Genetic counseling and genetic testing are recommended for families that meet the Amsterdam criteria, preferably before the onset of colon cancer.

The following are the Amsterdam criteria in identifying high-risk candidates for molecular genetic testing:

"Amsterdam Criteria (all bullet points must be fulfilled):"

- Three or more family members with a confirmed diagnosis of colorectal cancer, one of whom is a first degree (parent, child, sibling) relative of the other two

- Two successive affected generations

- One or more colon cancers diagnosed under age 50 years

- Familial adenomatous polyposis (FAP) has been excluded

"Amsterdam Criteria II (all bullet points must be fulfilled):"

- Three or more family members with HNPCC-related cancers, one of whom is a first-degree relative of the other two

- Two successive affected generations

- One or more of the HNPCC-related cancers diagnosed under age 50 years

- Familial adenomatous polyposis (FAP) has been excluded

A number of genes are associated with HBOC. The most common of the known causes of HBOC are:

- BRCA mutations: Harmful mutations in the "BRCA1" and "BRCA2" genes can produce very high rates of breast and ovarian cancer, as well as increased rates of other cancers.

Other identified genes include:

- "TP53": Mutations cause Li-Fraumeni syndrome. It produces particularly high rates of breast cancer among younger women with mutated genes, and despite being rare, 4% of women with breast cancer under age 30 have a mutation in this gene.

- "PTEN": Mutations cause Cowden syndrome, which produces hamartomas (benign polyps) in the colon, skin growths, and other clinical signs, as well as an increased risk for many cancers.

- "CDH1": Mutations are associated with lobular breast cancer and gastric cancer.

- "STK11": Mutations produce Peutz–Jeghers syndrome. It is extremely rare, and creates a predisposition to breast cancer, intestinal cancer, and pancreatic cancer.

- "CHEK2": Approximately one out of 40 northern Europeans have a mutation in this gene, making it a common mutation. Considered a moderate-risk mutation, it may double or triple the carrier's lifetime risk of breast cancer, and also increase the risk of colon cancer and prostate cancer.

- "ATM": Mutations cause ataxia telangectasia; female carriers have approximately double the normal risk of developing breast cancer.

- "PALB2": Studies vary in their estimate of the risk from mutations in this gene. It may be moderate risk, or as high as "BRCA2".

Approximately 45% of HBOC cases involve unidentified genes, or multiple genes.

A 2009 revision of the traditional Chompret criteria for screening has been proposed:

A proband who has:

- tumor belonging to the LFS tumor spectrum - soft tissue sarcoma, osteosarcoma, pre-menopausal breast cancer, brain tumor, adrenocortical carcinoma, leukemia or lung bronchoalveolar cancer - before age 46 years;

and at least one of the following:

- at least one first or second degree relative with an LFS tumour (except breast cancer if the proband has breast cancer) before age 56 years or with multiple tumours

- a proband with multiple tumours (except multiple breast tumours), two of which belong to the LFS tumour spectrum and the first of which occurred before age 46 years

- a proband who is diagnosed with adrenocortical carcinoma or choroid plexus tumour, irrespective of family history