Cancer refers to malignant neoplasms that tend to invade surrounding tissues and that metastasize to new body sites. They are likely to recur after attempted removal and to cause death of the patient unless adequately treated. The exact cause of cancer is not known, but links between certain activities such as smoking or exposure to carcinogens and the incidence of certain types of cancers and tumors have been shown by a number of researchers.
The spread of cancer from a primary site to distant organs, i.e., metastasis, still remains the main cause of death for most cancer patients. Despite years of research, the genetic mechanisms involved in the process remain largely uncharacterized. Such information is of special importance in cancer prognosis given the uncertain course of the disease. Since cancer prognosis cannot always be accurately assessed using current tumor grading techniques, one of the greatest obstacles to the successful treatment of the cancer patient continues to be the lack of sound prognostic markers.
Bladder Cancer
Bladder cancer is a malignant tumor growth which usually arises from the urothelial cells, (transitional cells) that line the bladder. Urothelial carcinoma of the bladder, i.e. bladder cancer, is the fourth most common cancer in men and the eighth most common cancer in women in the United States, accounting for more than 54,000 new cases and 11,200 deaths every year. Recurrences of bladder cancer occur in up to 80% of patients and constitute a formidable obstacle to long-lasting remissions, with such recurrences frequently involving muscle invasion and disseminated disease (Dawson et al., ABC of Urology: Urological Malignancies-II: Urothelial Tumors. BMJ, 1996, 312: 1090–94).
Numerous factors may contribute to the development of bladder cancer. Cigarette smoking and occupational exposure to a certain class of organic chemicals called aromatic amines (beta-naphthylamines, xenylamine, 4-nitrobiphenyl, benzidine) are well-established risk factors. Some studies indicate that there may be a link between high doses of the artificial sweetener saccharin and transitional cell bladder cancer. Other studies have shown that women who received radiation therapy for the treatment of cervical cancer have an increased risk of developing transitional cell bladder cancer. Additionally, people who received the chemotherapy drug, cyclophosphamide (Cytoxan), have demonstrated a greater risk of developing bladder cancer.
The most common clinical presentation of bladder cancer is hematuria. Frequently, however, the diagnosis of bladder cancer is delayed because the hematuria is either intermittent or attributed to other causes, such as a urinary tract infection or the use of anti-coagulants. Voided urine cytology of transitional cells is conventionally used to diagnose bladder cancer. If the urinary cytology is positive, then transitional cell cancer of the urothelium is almost certainly present. However, cytological examination of transitional cells may be negative in up to half of the patients with bladder cancer. Thus, negative cytological results do not rule out the presence of bladder cancer (Badalament et al., Cancer, 1987, 59(12): 2078; Cohen et al., Urologic Clinics of North America, 1992, 19(3): 421).
As an added diagnostic complication, the entire urinary tract must be evaluated for transitional cell cancer once an initial diagnosis of bladder cancer is made because transitional cells line the urinary tract starting at the level of the kidneys, including the renal pelvis, the ureters, the bladder, and most of the urethra. The renal pelvis of the kidneys and ureters is best evaluated by intravenous pyelogram (IVP) or retrograde pyelogram. An IVP involves an intravenous injection of contrast material which is then filtered out of the blood into the urine by the kidney. Plain x-rays taken during this process show the urinary tract. Typically a retrograde pyelogram is reserved for patients with an intravenous contrast allergy or poor visualization on IVP. A retrograde pyelogram is performed at the time of cystoscopy.
Cystoscopy, which involves the use of a lighted instrument to view inside the bladder, is an uncomfortable procedure utilized for the unambiguous diagnosis of bladder cancer. In performing a retrograde pyelogram through the cystoscope a small plastic tube is inserted into the ureter, and contrast material is injected into the ureter and kidney. Cystoscopy enables the identification of small subtle abnormalities that may be missed by other diagnostic modalities such as ultrasound, computed tomography, or magnetic resonance imaging. Thus, office cystoscopy is an essential part of the initial evaluation and at this time cannot be substituted by other tests. Today, most office cystoscopic examinations are performed with a flexible scope. Compared to rigid cystoscopy, flexible endoscopy is more comfortable and allows the physician to see around the curves of an enlarged prostate.
A biopsy may also be performed to diagnose bladder cancer. A biopsy is the removal of a small sample of living tissue from an organ, such as the bladder, for microscopic examination to confirm or establish a diagnosis, estimate prognosis, or follow the course of a disease. However, biopsies are invasive procedures, and are therefore not desirable and it frequently is necessary for a person to undergo anesthesia. In addition, as with any invasive procedure, an individual undergoing biopsy runs the risk of infection. Further, the entire bladder cannot be biopsied to determine whether bladder cancer is present.
Staging Bladder Cancer
Bladder cancers are classified based on their aggressiveness and how different they are from the surrounding bladder tissue (differentiation). They are staged and graded by physicians while diagnosing bladder cancer.
There are several different ways to stage tumors. The two most commonly used staging systems for bladder cancer are the ABCD system (the Jewett-Strong-Marshall system) and the TNM system. The ABCD system is older and uses A-B-C-D staging to classify the distinct phases or periods of bladder cancer. The system basically uses the following scale: 0, carcinoma in situ (tumor limited to the bladder mucosa (lining)); A, tumor extends through the mucosa but does not extend beyond the submucosa; B, tumor invades the muscle; C, tumor invades into the fat; and D, cancer has spread to regional lymph nodes or to distant sites. Each letter is followed by a number, for example A1, B2, etc. With the TNM system, the bladder is described by the T, the lymph nodes by the N, and distant spread by the M. Each letter is followed by a describing number, T2aN0M0. For example, Ta denotes a non-invasive papillary carcinoma; Tis denotes a carcinoma in situ; and T1 denotes a tumor invading subepithelial connective tissue.
Bladder cancers spread to the rest of the body by extending into the nearby organs, including the prostate, uterus, vagina, ureters, and rectum. Metastasis occurs through the pelvic lymph nodes, where the tumor next spreads to the liver, lungs and bones.
Grading Bladder Cancer
Bladder cancers are graded by a pathologist from the biopsy. The grade of a cancer provides information regarding how fast the cancer might be growing or how aggressive it might be. High grade cancers grow faster and spread earlier than low grade cancers. The current system of grading uses only three different grades: well-differentiated, moderately differentiated, and poorly differentiated (or Grade I, II or III). Some pathologists will use a 4-level grading system, I, II, III and IV. Either system is acceptable, and the pathologist will always note how many levels they use by declaring the cancer as a II/III or II/IV. The denominator or second number states what system they use. A well-differentiated tumor means that the cancer has more resemblance to normal bladder tissue and therefore usually does not grow or spread quickly. A poorly differentiated tumor means that the cancer does not resemble normal bladder and usually grows quickly and spreads to other tissues earlier. Moderately differentiated tumors are in the middle.
Grade, while important, has less bearing on the treatment decisions than does the stage. After the grade and stage are known, other factors also come into play before making any decision about future treatment.
Prostate Cancer
Prostate cancer is a malignant tumor growth within the prostate gland. It is the third most common cause of death from cancer among men of all ages and is the most common cause of death from cancer in men over 75 years old. Prostate cancer is rarely found in men younger than 40 years of age.
Although the cause is unknown, some studies have shown a relationship between prostate cancer and high dietary fat intake and increased testosterone levels. There is no known association with benign prostatic hyperplasia (BPH).
Like bladder cancer, prostate cancers are classified or staged based on their aggressiveness and the degree that they are different from the surrounding prostate tissue. Most prostate cancers are staged using the A-B-C-D staging system or the TNM system. For prostate cancer, the A-B-C-D system basically categorizes tumors using the following scale: A tumor not palpable (able to be felt) but detectable in microscopic biopsy; B palpable tumor confined to prostate; C extension of tumor beyond prostate with no distant metastasis; and D cancer has spread to regional lymph nodes. The TNM system, on the other hand, describes the prostate (T), the lymph nodes (N), and evidence of metastatic disease (distant spread) (M) separately. Prostate cancers spread by extending into the seminal vesicles, bladder, and peritoneal cavity. Prostate cancers typically metastasize to the lymph nodes, bones, lungs, liver, and kidneys.
Today, prostate cancer is usually graded using the Gleason grading system, named after a pathologist from the University of Minnesota. The system involves looking for different patterns of aggressiveness within the prostate and then giving two scores of 1–5. These two scores are added up to give the total Gleason score which will range from 2–10. The higher the score, the more aggressive the tumor will be. For example, a typical Gleason graded cancer might be written as Gleason 4+3=7, or Gleason 2+2=4.
Survivin
Deregulated expression of inhibitors of apoptosis (programmed cell death) is thought to contribute to cancer by abnormally extending cell viability, favoring the accumulation of mutations, and promoting resistance to therapy (Reed, J. Clin. Oncol., 1999, 17: 2941–53). A novel modulator of the cell death/viability balance in cancer was recently identified as survivin (Ambrosini et al., Nat. Med., 1997, 3: 917–21), a member of the Inhibitor of Apoptosis (IAP) gene family (Deveraux et al., Genes Dev., 1999, 13: 239–52).
Survivin is a 16.5 kDa cytoplasmic protein containing a single partially conserved BIR (baculovirus IAP repeats) domain, and a highly charged carboxyl-terminal coiled-coil region instead of a RING finger, which inhibits apoptosis induced by growth factor (IL-3) withdrawal when transferred in B cell precursors (Ambrosini et al., Nat Med 1997, 3:917–921). Based on overall sequence conservation, the absence of a carboxyl-terminal RING finger and the presence of a single, partially conserved BIR domain, survivin is the most distantly related member of the IAP family, sharing the highest degree of similarity with NAIP (neuronal apoptosis inhibitory protein; Roy et al., Cell, 1995, 80:167–178). Additionally, unlike other IAP proteins, survivin is undetectable in normal adult tissues, but becomes the top fourth transcript expressed in common human cancers (Ambrosini et al., Nat. Med., 1997, 3: 917–21; Velculescu et al., Nat. Genet., 1999, 23:387–88), such as lung, colon, breast, pancreas, and prostate, and in ˜50% of high-grade non-Hodgkin's lymphomas, in vivo. Consistent with a proposed role of deregulated apoptosis in urothelial cancer (Gazzaniga et al., Int. J. Cancer, 1996, 69:100–04; Lara et al., Int. J. Radiat. Oncol. Biol. Phys., 1999, 43:1015–19), survivin was found in 78% of bladder cancers, but not in normal urothelium, and its expression correlated with accelerated recurrences (Swana et al., N. Engl. J. Med., 1999, 341:452–53). Because of its over-expression in cancer but not in normal tissues (Ambrosini et al., Nat. Med., 1997, 3:917–21; Velculescu et al., Nat. Genet., 1999, 23:387–88), and its unfavorable predictive/prognostic significance in various malignancies (Adida et al, Lancet, 1998, 351: 882–83; Islam et al., Oncogene, 2000, 19:617–23; Tanaka et al., Clin. Cancer Res., 2000, 6: 127–34; Monzo et al., J. Clin. Oncol., 1999, 17: 2100–04; Kawasaki et al., Cancer Res., 1998, 58: 5071–74), survivin may constitute a useful molecular marker in cancer. This is particularly relevant in bladder cancer (Stein et al., J. Urol., 1998, 160: 645–59; Ozen, Curr. Opin. Oncol., 1998, 10: 273–78) where simple and non-invasive diagnostic means to monitor response to therapy and simplify follow up protocols are urgently needed. Although regarded as “gold standard” (Brown, Urol. Clin. North Am., 2000, 27: 25–37), urine cytology has a low sensitivity (30–40%) in bladder cancer, and fails to detect superficial, low-grade lesions. Accordingly, the inventors of the instant application investigated the potential suitability of bodily fluid survivin as a new molecular marker for detection of cancer, specifically detection of urine survivin for the diagnosis of bladder cancer.