Radioimmunoscintigraphy using Prostascint (Capromab Pendetide) Essay Example for Free

Radioimmunoscintigraphy using Prostascint (Capromab Pendetide) EssayAbstract Prostate cancer is one of the most common malignancies encountered among the men over the age of 65 grades in the U.S. Proper give-and-take of patients with prostate gland cancer requires the determination of exact extent of cancer riddle. Conventional visualize modalities like CT and MRI postulate proved to be of little lend oneself. Newer imaginativeness modality involving piano tunerimmunoscintigraphy using Prostascint has emerged as a useful symptomatic rill for management of cases of carcinoma of prostate, particularly patients with localized disorder and those showing evidence of recurrence fol sufferinging radiotherapy. Prostascint resource serves as a reliable, noninvasive means of antitheticiating patients with organ-confined complaint from those with metastatic spread to lymph. Following a dictatorial Prostascint run over confirmatory studies (biopsy of involved sites) must be un dertaken antecedent to initiation of a unequivocal surgical procedure. In the modern era, gamy quality consolidated externalizes, using CT or MRI with Prostascint run overs, obtained from using higher-resolution gamma cameras, have further increased the value of radioimmunoscintigraphy. scarcely well designed randomized controlled trials in future are take to prove the exact clinical role of Prostascint imaging in cases of prostate cancer. hedge of contentsIntroduction.4Analysis of Prostascint tomography.5Applications of Prostascint imaging6Newly diagnosed patients with biopsy-proven prostate cancer.6Patients with acclivitous levels of prostate specific antigen following prostatectomy..7Challenges associated with the use of Prostascint imaging..10Safety and precautions.11 culture13References/ bibliographyl5Radioimmunoscintigraphy using Prostascint (Capromab Pendetide)IntroductionProstate cancer is one of the most common malignancies encountered among themen over the age of 65 years in the U.S. During the year 2004, in the U.S 230,110 men were registered with the diagnosis of carcinoma prostate, whereas 29,900 died from it. (Jemal et al, 2004). Following the diagnosis of prostate cancer, one of the most important challenges for the clinician is to estimate the exact extent of the cancer (cancer staging) in pronounce to undertake a proper treatment plan, which would be able to cure the cancer in its entirety in early as well as late cases. Information needed to stage prostate cancer depends upon tumor size, location, extra-prostatic extension, lymphatic involvement and distant metastases (Neal Kelly, 2004). In more than one third of cases of prostate cancer, by the time cancer is diagnosed, it has frequently involved the lymph nodes outside the pelvis, the most common ones organism the periaortic lymph nodes (Neal Kelly, 2004).Treatment options and prognosis of localized cancer of prostate is different from the cases where the cancer has spread into the lymph nodes, contradicting the use of two surgery and radiotherapy, which works well for the localized complaint. Hormone therapy and deep taxane based chemotherapy is used for the treatment of advanced disease (Neal Kelly, 2004). Presently the prediction of lymph node metastasis is not very accurate because, in the vast majority of cases, tissue inquiry for evaluating spread of cancer is based on biopsies involving a limited sample of the area with possible lymphatic spread.Conventional imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) for detecting low-keyed tissue metastasis, suffer from many disadvantages, which limits their use for this purpose (Neal Kelly, 2004). Lymphography as a diagnostic modality for visualization of lymphatic vessels and lymph nodes, following injection of radio opaque material in a lymphatic vessel has also proven to be inaccurate (Wolfgang, 2003). Significant advancements in the field of medical imaging ha ve enabled the accurate estimation of cancer spread to a large extent. One such imaging technology is radioimmunoscintigraphy with Prostascint, which would be discussed in this paper.Analysis of Prostascint ImagingRadioimmunoscintigraphy is a thermo thermonuclear medicine imaging technique which detectsnsignal from a radio labeled antibody that recognizes prostate tissue (Wolfgang, 2003). The most unremarkably studied monoclonal murine antibody for this purpose is (7E11-C53), capromab pendetide conjugated with the linker-chelator glycyl-tyrosyl-(N, -diethylenetriamine-pentaacetic acid)-lysine commonly known as Prostascint. In the most commonly used type of radioimmunoscintigraphy, Prostascint which has been radio labeled with indium-111(In-111) is given, followed by nuclear medicine imaging or SPECT imaging (Keane, Rosner, Wingo, McLeod, 2006).The most studied target for prostate cancer is the prostate-specific membrane antigen (PSMA), a glycoprotein expressed by prostate tissue, which is produced both by benign and malignant prostate epithelial cells. However it is expressed more abundantly in patients with prostate cancer, hormone-refractive disease, and prostate cancer metastases (Keane et al, 2006). Thus immunoscintigraphy is dependent on the degree of PSMA expression rather than the actual size of a metastatic lesion or the increase in the levels of PSA (prostate specific antigen).Applications of Prostascint imagingProstascint (Capromab Pendetide) is commonly used as a diagnostic imaging agent, which shows significantly improved aesthesia for extra-prostatic cancer detection compared with conventional imaging modalities (Keane et al, 2006). According to the literature canvass by Keane et al, (2006), Prostascint, conveyd Food and Drug Administration (FDA) approval in 1996 for its use as an imaging agent for the following purposes(1) For the staging of patients, who have been recently diagnosed with histologically proven localized prostate cancer and are at a high risk for soft tissue metastases or(2) For the restaging of post prostatectomy patients with a rising PSA level. These applications of Prostascint have been described below in detailsNewly diagnosed patients with biopsy-proven prostate cancerProstascint imaging should be considered afterwards a definitive diagnosis of localizedprostate cancer, as proven by standard diagnostic investigations including chest x-ray, fancy up scan, CT scan, or MRI, which have been made prior to the initiation of definitive therapy in form of surgery or radiotherapy. Prostascint is not indicated in patients who are not at high risk for developing metastatic disease (Hinke et al, 1998). In fact it is especially administered to those patients who are at a high risk for pelvic lymph node metastasis as shown by an intermediate to high Gleason grade (a system for grading prostate cancer depending on the degree of differentiation of the malignant cells under a microscope) or by other diagnostic investigations carried out to evaluate the disease spread. In a study by Hinke et al (1998), scan confirmatory extraprostatic regions, especially lymph nodes, following initial treatment, were histologically evaluated.The sensitivity and specificity of Prostascint imaging in detection of extraprostatic disease was found to be 75% and 86% respectively, whereas the accuracy was found to be 81% and the positive predictive of Prostascint imaging in detection of extraprostatic disease was found to be 79%. Thus, the study by Hinke et al (1998) shows that In-111 capromab pendetide (Prostascint) imaging has emerged as a promising diagnostic neb for detecting prostate cancer by having a significant impact on patient management through its detection of occult extra-prostatic disease in more than 50% of prostate carcinoma patients studied, and information regarding the heraldic bearing of lymph node metastasis.It also shows that Prostascint imaging serves as a reliable, noninvasive means of differentiating patients with organ-confined disease from those with metastatic spread to lymph nodes and complements other modalities including prostate specific antigen (PSA), Gleason score, and clinical staging. Since Prostascint imaging can help predict the future involvement of lymph nodes in patients at high risk for extraprostatic disease it can therefore help in the selection of patients who whitethorn not benefit from definitive local therapy in form of surgery or radiotherapy.Patients with rising levels of PSA following prostatectomyDespite the ability of topic prostatectomy to eradicate prostate carcinoma, biochemical evidence of recurrent prostate carcinoma, in form of elevation in the serum PSA levels above the limit of detection may be seen in approximately 40% of patients, 15 years after they undergo surgery. The PSA test may become positive many years prior to a change in the bone scan or before the subject of clinical evidence of recurrence (Neal Kelly, 2004). In more than 33% of cases the disease may recur locally in the prostatic fossa or regional lymph nodes or at distant sites.The presence of cancer recurrence requires further treatment in form of local salvage treatments or systemic therapy (Neal Kelly, 2004). carry through therapy in form of external beam radiation may provide a therapeutic benefit only to those patients who have a localized recurrence. On the other hand, systemic therapy like hormonal therapy is usually recommended for patients with disseminated disease (lymphatic or metastatic spread) (Neal Kelly, 2004). Traditionally, most patients who show elevated serum levels of PSA post-surgically undergo a computed tomography (CT) scan of abdomen and pelvis or bone scintigraphy.The detection of tumor deposits on CT scans is size dependent i.e. the size of the tumor deposits should be more than 1015 mm prior to detection. Further more, CT scan is not able to differentiate whether the lymph node is enlarged due to the prese nce of inflammation or metastasis (Neal Kelly, 2004). Thus the finding of radiographically enlarged lymph nodes is not diagnostic of carcinoma.Recurrence of prostate cancer after radiotherapy presents several challenges for the clinician regarding appropriate management. It is of achievement importance to identify correctly those patients with persistent localized disease and the potential to benefit from curative therapy (Keane et al, 2003). The localization of the extent of recurrent disease after radical prostatectomy is especially important for patients showing rising levels of PSA after prostatectomy and are being considered for salvage radiation therapy. However this is difficult with presently available techniques and may greatly influence subsequent clinical management (Raj, Partin, Polasiik, 2002).Prostascint imaging would greatly help in providing solution to this problem. Patients showing a positive result with radioimmunoscintigraphy, demonstrating that the cases with disease spread outside the pelvis can be spared irrelevant treatment, with radiotherapy, thus helps in reducing the associated morbidity and expense (Keane et al, 2006). Raj et al (2002) conducted a study to understand the use of indium- 111 labelled Prostascint imaging to detect recurrent prostate carcinoma radiographically in men with early biochemical evidence of failure (serum PSA levels less than or equal to 4.0 ng/mL) and tried to assess the minimum rise in serum PSA level, which would be necessary for imaging recurrent disease.Preoperatively, all patients had damaging bone scans and negative lymph nodes on histopathological biopsy, and they did not undergo any therapy including hormonal ablation, chemotherapy, or radiation therapy preoperatively or postoperatively until the (111)In labeled Prostascint imaging was performed. The results of this study present that the Prostascint imaging is capable of detecting recurrent disease irrespective of level of serum PSA increase. Postive results on prostascint imaging were associated with significant increase in the prospect of having recurrent disease.Furthermore 42.8% of patients demonstrated regional uptake in prostatic fossa with or without regional lymph nodes. Almost one-third of patients (30.6%) had local uptake only in the prostatic fossa. These results are in agreement with the known fact that one-third of prostate tumors that recur after prostate surgery occurs locally inwardly the prostatic bed. Thus a positive Prostascint scan results can help classify the patients into two clinically useful categories, i.e. those with local disease and those with distant recurrent disease, which are candidates for subsequent salvage treatment protocols.Challenges associated with the use of Prostascint imaging Imaging with indium In-111 capromab pendetide is technically challenging, requiring high degree of attention to anatomicalal details, which is not normally necessary with most nuclear medicine studies. The image quality of Prostascint imaging is detect to widely vary among different institutions depending on the method of image acquisition, the skills of the interlingual rendition radiologist, and the resolution of cameras used for SPECT scanning (Wong, Turkington, Polascik, Coleman, 2004).Thus Prostascint imaging requires special training of the involved health fretfulness professionals in the field of nuclear medicine, utilizing this technique. Interpretation of the images requires the nuclear medicine physician to become familiar with detailed anatomy of the pelvis in order to read through the normal uptake patterns seen with this drug. On being given sufficient training and experience, the study can become routine for most nuclear medicine departments.Some of the limitations associated with the use of Prostascint scan include, relatively low spatial resolution and low detection efficiency of medium-energy collimators used in the past for detection of In-111 photo peaks non specific localization of monoclonal antibodies in the blood, bowel, bone marrow, and prostate gland and lack of anatomic information on the part of the radiologist to localize accumulation of radiotracer (Wong et al, 2004).In order to improve upon the image quality, diagnostic accuracy and to discover a practical and efficient method of imaging, free from the above described problems, increasing degree of research has been done to improve image resolution. Over the past 5 years, significantly greater image resolution from improved camera technology and the use of co-registration to fuse functional images provided by radioimmunoscintigraphy with anatomic imaging scans such as CT or MRI (Wong, et al 2004).The fusion of these images helps in fusion of anatomical image (obtained on CT or MRI) and physiological image (obtained through Prostascint imaging), thereby considerably improving the resolution of fused image. Keane et al (2006) have reported an accuracy of 83% with fused images. The use of dual-head gamma cameras with a much higher resolution, to co-register the functional single-photon emission tomography (SPECT) image and an anatomic image (CT or MRI) has also made a striking difference in prostate cancer detection with the Prostascint imaging (Keane, (2006). Wong et al (2004) conducted a study in which they tried to improve the diagnostic accuracy of this examination by using hybrid gamma cameraCT technology. Imaging was performed on a dual-head scanner with an integrated CT scanner built onto the identical rotating gantry as the camera heads (for SPECT scanning).Wong et al reached the conclusion that evaluation of extraprostatic disease in the pelvis and lower abdomen may also be facilitated by the combined SPECT-CT images. However, the sample size of this study was too small to reach any definitive conclusion. In future, larger well designed, randomized controlled studies are indispensable in order to definitely prove the advantage of this type of s canning in comparison to conventional Prostascint imaging.Safety and precautionsCertain precautions which must be observed at the time of Prostascint imaging ashighlighted in a study by Raj et al (2002) are as followsPrior investigations have demonstrated that 111In-capromab pendetide immunoscintigraphy is safe, with flabby adverse effects and minimal increase in the levels of antibodies directed against murine antibody levels (Raj et al, 2002). There is a theoretical risk for occurrence of allergic reactions, including anaphylaxis, in patients who receive murine antibodies. Although serious reactions of this type have not been observed in clinical trials after administration of Indium In-111 Prostascint, Raj et al (2002) have suggested that emergency medications for the treatment of anaphylactic reactions should be available during administration of this agent. confirmatory trials in the futureDue to difficulties in image interpretation, Prostascint imaging is associated with high rate rates of false positive and false negative image interpretation results. Thus patient management should not be solely based on ProstaScint scan results without appropriate descriptor three confirmatory trials in the future. Positive Prostascint scan results should be followed by further confirmatory tests (e.g. histopathological analysis). Also these images should be interpreted only by physicians who have had specific training in Indium In-111 Prostascint image interpretation.High False positive scan rates associated with Prostascint may be detrimental to patient care by resulting in inappropriate surgical intervention in patients who had been cured of their primary cancer and have no cancer recurrence. On the other hand, inappropriate denial of curative therapy may occur in case results are not confirmed. Positive Prostascint scanning can also result in unsuitably high stage on surgical staging if only areas of uptake are sampled. Surgical sampling should not be limited to the areas of positive uptake, unless histologic examination Of these areas has yielded positive resultsBone scans are more sensitive than Prostascint scanning for the detection of metastases to bone. Thus Prostascint scanning should not replace bone scan for the evaluation of skeletal metastases.Prostascint imaging involves use of radiopharmaceuticals, which must be used only by physicians and other health care professionals who are qualified for treatment and using radionuclides. Care should be taken to minimize radiation exposure to patients and medical personnel, consistent with proper hospital and patient management procedures.Due to detain clearance of In- 111 Prostascint and post scan localization in the bowel, blood , kidneys, and bladder, most researchers suggest that bladder should be catheterized and irrigated when obtaining SPECT images. A cathartic must also be administered the evening before imaging the patient, and a cleansing enema should be administered within an ho ur prior to each imaging session.ConclusionFrom the above news it becomes apparent that Prostascint imaging using indium In-111 capromab pendetide offers important additional information to physicians who treat and manage prostate carcinoma patients. In the patients with primary disease, prostascint imaging should be considered after a definitive diagnosis of cancer has been made, prior to surgery or radiation therapy, when there is high risk for pelvic lymph node metastasis. Prostascint imaging serves as a reliable, noninvasive means of differentiating patients with organ-confined disease from those with metastatic spread to lymph nodes and complements other indicators of metastatic disease like PSA, Gleason score etc.A positive Prostascint scan serves as an indicator for undertaking confirmatory studies (biopsy of involved sites) prior to initiation of a definitive surgical procedure. In the modern era, high quality fused images (with CT or MRI) obtained from using higher-resolut ion gamma cameras, have confirmed the value of radioimmunoscintigraphy. However well designed randomized controlled trials in future are required to prove the exact clinical role of Prostascint imaging in cases of prostate cancer.ReferencesHinke, G.H., Burgers, J.K., Neal, C.E., Texer, J.H., Kahn, D., Williams, R.D., et al.(1998). Multicenter radioimmunoscintigraphic evaluation of patients with prostate carcinoma using indium-111 capromab pendetide. Cancer, 83(4), 739-747.Jemal, A., Tiwari, R.C., Murray, T., Ghafoor, A., Samuels, A., Ward, E. et al (2004).Cancer Statistics, 2004. Cancer Journal for Clinicians, 54, 8-29.Keane, T.E., Rosner, I.L., Wingo, M.S., McLeod, D. J. (2006). The event ofRadioimmunoscintigraphy for Prostate Cancer. Reviews in Urology, 8 (Suppl 1), S20S28.Neal, D.E., Kelly, J.D.(2004). The prostate and seminal vesicles. In Russell, R.C.G.,Williams, N. S., Bulstrode (Eds.), C.J.K.Bailey and Love Short Practice of Surgery. 24th Edition. (pp. 1370-1387). London Oxford University Press.Raj, G.V., Partin, A.W., Polasiik, T.J. (2002). Clinical utility of indium 111-capromabpendetide immunoscintigraphy in the detection of early, recurrent prostate carcinoma after radical prostatectomy. Cancer, 94(4), 987-96.Wolfgang, Dahnert. 2003. Radiology review manual Nuclear medicine. 5th Edition.Philadelphia Lippincott Williams and Willikins (pp.1080).Wong, T.Z., Turkington, T.G., Polascik, T.J., Coleman, R.E. (2005). Prostascint(Capromab Pendetide) Imaging Using Hybrid Gamma tv cameraCT Technology. AJR, 184, 676-680.