Whole abdominopelvic radiotherapy in the palliative treatment of pseudomyxoma peritonei.

BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare clinical syndrome characterized by mucinous peritoneal disease arising from disseminated peritoneal adenomucinosis. Primary treatment involves a combination of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC). There is no consensus on the proper treatment of recurrent PMP. In selected patients, repeated cytoreductive surgery with or without HIPEC might improve outcome. However, every repeated debulking procedure becomes less effective with increased morbidity. CASE REPORT: We present a case of a patient with intestinal obstruction caused by recurrent pseudomyxoma peritonei. We treated the patient with whole abdominopelvic radiotherapy (WAPRT) using intensity-modulated arc therapy (IMAT) to a total dose of 33 Gy, delivered in 22 daily fractions. The treatment was well tolerated and resulted in resolution of the obstruction for a period of 24 months. CONCLUSION: To the best of our knowledge, we present the first case report showing the possibility of resolving intestinal obstruction with WAPRT in a patient with recurrent PMP. It is our opinion that WAPRT delivered by IMAT, in analogy with ovarian cancer, should be considered as a palliative treatment option in managing patients with recurrent PMP especially in case of obstruction.

Incidental finding of pseudomyxoma peritonei at primary cesarean section.

Primary appendiceal carcinoma is extremely rare and is found in approximately 1% of appendectomy specimens. When cancer is present, the most frequent histology is mucinous adenocarcinoma. Neoplasms of the appendix that secrete mucin such as adenocarcinoma may rupture, leading to intraperitoneal seeding of the peritoneum and producing the clinical picture of pseudomyxoma peritonei (PMP). PMP is characterized by mucin-producing neoplastic cells that have seeded the peritoneum from the ruptured viscous and continue to secrete copious amounts of gelatinous material that accumulates in the abdomen producing the characteristic "jelly belly." A review of the medical literature revealed no cases of PMP diagnosed at time of cesarean section. A previously healthy gravida 5, para 3 underwent cesarean section. Upon opening of the peritoneum, copious amounts of gelatinous, yellow-tinged mucoid material was noted. A general surgeon was consulted, and grossly necrotic-appearing appendix was noted. The patient underwent appendectomy with right hemicolectomy. Pathology showed well-differentiated mucinous adenocarcinoma of the appendix. PMP is associated with gastrointestinal and ovarian carcinomas. Although somewhat rare, these cancers may occur in pregnancy. Because nonspecific abdominal pain and increasing abdominal girth are common in pregnancy, patients' complaints may go ignored. Early diagnosis of a potentially life-threatening disease requires that clinicians expand the differential diagnosis and consider the possibility of a malignant neoplasm presenting in the pregnant female.

Occult primary adenocarcinoma causing pseudomyxoma peritonei with pleural and hepatic metastases.

Pseudomyxoma peritonei is characterized by diffuse collections of gelatinous flux resulting from implantation of malignant tumors or irritation from ruptured benign cysts. We report a patient with pseudomyxoma peritonei caused by an occult primary adenocarcinoma, who had both pleural and hepatic metastases.

Absorbed dose estimates for 131I-labelled monoclonal antibody therapy in patients with intraperitoneal pseudomyxoma.

Seven patients with intraperitoneal pseudomyxoma originating from the appendix (4 cases) and from the ovary (3 cases) were treated with radioimmunotherapy. During the therapy, nine infusions of 3.0-4.2 GBq of 131I-labelled B72.3 monoclonal antibody were administered. We developed three-dimensional dose calculation software that can utilize activity maps based on SPET images to calculate the absorbed dose distribution using point source kernels. The dose calculation program was employed to calculate absorbed doses to various organs. The calculated dose distributions enable us to evaluate the variation in dose within the organs, which is normally not available using approaches based on geometric models. The patient-specific absorbed dose calculations were compared with doses based on a model that uses photon S-factors derived from a standard phantom. The compared doses agreed well on average, but in some organs showed large discrepancies.

The use of TL detectors in dosimetry of systemic radiation therapy.

A method for determining absorbed doses to organs in systemic radiation therapy (SRT) is evaluated. The method, based on thermoluminescent (TL) dosimeters placed on the patient's skin, was validated and justified through a phantom study showing that the difference between measured (TL dosimeters in the phantom) and derived (TL method) values is within 10%. Six radioimmunotherapy (RIT) patients with widespread intraperitoneal pseudomyxoma were also studied. In dose evaluations, special emphasis was on kidneys. In addition to the TL method, the absorbed doses to kidneys were calculated using MIRD formalism and a point dose kernel technique. We conclude that in SRT the described TL method can be used to estimate the absorbed doses to those critical organs near the body surface within 50% (1 SD).

The effect of three dimensional activity distribution on the dose planning of radioimmunotherapy for patients with advanced intraperitoneal pseudomyxoma.

BACKGROUND: Six patients with histologically proven peritoneal carcinomatous pseudomyxomas were treated with radioimmunotherapy. METHODS: All the patients received a tracer dose of iodine-131 (131I) labeled B72.3 anti-TAG-72 monoclonal antibody (MoAb) to test the in vivo affinity. After informed consent was obtained the therapeutic dose (>3.7 gigabecquerels [GBq], 100 mCi) of the 131I labeled B72.3 anti-TAG-72 MoAb was infused within 60 minutes intraperitoneally using 2 catheters on both sides of the abdomen. The patients were imaged with single photon emission computed tomography (SPECT) at 3, 10, and 24 days after the therapeutic infusion. Treatment-planning software has been developed in which functional information obtained from SPECT is integrated with anatomic information obtained from computed tomography (CT). The activity distribution from SPECT images is converted to absorbed dose distributions using a point source kernel convolution dose calculation. The absorbed dose calculation requires a radionuclide specific dose kernel. The activity map is divided into equally sized source voxels from which the distribution is calculated for the target voxels that cover the patient volume. The resulting three dimensional (3D) absorbed dose distribution is viewed as isodose contours superimposed on the CT images or as 3D isodose surfaces. RESULTS: The measured activity distribution shows that the cumulated activity and biologic half-life vary in the patient's body. The developed planning system provides a method for calculating patient specific absorbed dose distributions. CONCLUSIONS: The variation of biologic clearance indicates that a 3D dose calculation method incorporating measured activity distributions is needed to quantify absorbed dose distribution.

Radioimmunotherapy of solid cancers: A review.

Depending on radionuclide characteristics, radioimmunotherapy (RIT) relies on radioactivity to destroy cells distant from immunotargeted cells. Therefore, even heterogeneous tumors (for antigen recognition) can be treated, because not all cells have to be targeted. Substantial complete response rates have been reported in patients with non-Hodgkin's lymphoma. Much more modest results have been reported for patients with bulky solid tumors, e.g. adenocarcinomas. The radiation doses delivered by targeting antibodies are generally too low to achieve major therapeutic responses. Dose escalation is limited by myelotoxicity, and higher doses need to be delivered to neoplasms less radiosensitive than lymphomas. Various trials for both systemic and regional RIT have been reported on. Intraperitoneal administration has been applied for colorectal and ovarian carcinomas. Our own results indicate that, e.g., intraperitoneal pseudomyxoma can be treated with RIT. Myelotoxicity can be reduced by anti-antibody-enhancement, 2- and 3-step strategies, bispecific monoclonal antibodies (MAbs), and extracorporeal immunoadsorption. The radionuclide has to be selected properly for each purpose; it can be a beta-emitter, e.g. I-131, Y-90, Re-188, Re-186, Lu-177 or Sm-153, an alpha-emitter At-211 or Bi-212 or an Auger-emitter, e.g. I-125, I-123. One major problem with RIT, besides slow penetration rate into tumor tissue and low tumor-to-normal tissue ratio, is the HAMA response, which can be partly avoided by the use of humanized MAbs and immunosuppression. However, RIT will be, because of all the recent developments, an important form of cancer management.

Pseudomyxoma peritonei treated by radiotherapy.

Pseudomyxoma peritonei (PP) is a rare condition. Treatment is usually unsuccessful and the prognosis is poor. This report describes a patient who survived 16 years following their initial presentation.