Biomedical subjects
Publications and source records attributed to P P Kumar.
We present the technique, complications, and 5-year results of transperineal percutaneous template permanent interstitial iodine 125 endocurietherapy of localized prostate cancer in 85 treated patients. The 5-year outcome appears similar to that of external beam radiation therapy or radical surgery, but the iatrogenic mortality, morbidity, treatment time, and hospitalization are significantly reduced.
The authors report their initial treatment results in 49 patients with glioblastoma multiforme (GM) who received intraoperative endocurietherapy (ECT) with high-activity cobalt 60 (60Co) probe. Thirty poor prognosis (unresectable tumor) patients (Group I) with newly diagnosed GM were treated by either biopsy or subtotal excision, followed by 20.00-Gy single-fraction 60Co probe ECT, and 60.00-Gy external-beam radiation therapy (EXRT) (80.00 Gy total tumor dose). Nineteen patients (Group II) with recurrent, previously resected and externally irradiated GM were retreated with 20.00-Gy single-fraction 60Co probe ECT alone. The authors' initial experience with intraoperative ECT of GM is discussed.
Two cases of petroclival meningiomas are reported wherein the tumors were completely destroyed without surgical resection or external-beam irradiation by means of permanent stereotactic implantation of one or two high-activity iodine-125 seeds.
Inoperable solid tumor recurrence within a surgical bed or within a previously irradiated field usually responds poorly to re-treatment with conventional external beam irradiation (EXRT) and/or chemotherapy. We present a new, alternative method of re-treatment used in two patients with recurrent head and neck cancer involving the parotid (adenocarcinoma) and neck nodes (squamous cell carcinoma). These patients were successfully re-treated with high-activity 125iodine (I-125) permanent implantation.
Radiation therapy is considered the first treatment of choice for thoracic malignant diseases causing superior vena cava syndrome (SVCS). However, its use is poorly documented in cases in which intravascular tumor thrombosis is the major cause of obstructive symptoms. We report two cases of SVCS caused by thoracic malignancy. The first case failed to respond to the initial course of mediastinal radiation therapy. Contrast and radionuclide venography revealed two sites of tumor thrombosis located outside the radiation portal. Irradiation of these areas resulted in prompt relief of symptoms and complete relief of obstruction. In the second case, superior venacavogram and transluminal biopsy established the diagnosis and location of superior vena cava obstruction.
The significance of the contrast-enhancing ring seen on serial follow-up postirradiation computed tomograms (CT) of the brain was evaluated in a group of 41 patients with glioblastoma multiforme (GM) who were treated in a phase I/II study by means of intraoperative remote afterloading endocurietherapy (ECT) with a high activity cobalt 60 probe (20.00 Gy) in one high-dose rate fraction), and conventional fractionated external-beam (EXRT) radiotherapy (60.00 Gy in 30 fractions in 7.5 weeks). All received minimum total tumor doses of 80.00 Gy. After completion of treatment, all patients were followed with serial CT scans of the brain. Two to 6 months after treatment, 27 of 41 patients developed the similar thin-walled, regular, contrast-enhancing CT rings with low-density attenuation inside and outside the ring. Postmortem study in two of these patients revealed that the thin-walled, regular, contrast-enhancing ring represented a continuous capsule of dilated cerebral vessels with inner low-density attenuation corresponding to necrosis, and outer low-density attenuation corresponding to edema. The CT appearance of the thin-walled, regular, contrast-enhancing ring produced after high-dose rate intraoperative ECT and EXRT is distinctly different from the CT ring characteristic of untreated or recurrent GM. After high-dose rate intracranial ECT and EXRT, the appearance of a post-ECT contrast-enhancing CT ring should not be automatically interpreted as recurrent disease as previously reported after conventional fractionated EXRT.
Experience with endocurietherapy of skull base tumors is reviewed. We present our cases of recurrent pituitary hemangiopericytoma, radiation-induced recurrent meningioma, recurrent clival chordoma, recurrent nasopharyngeal cancer involving the cavernous sinus, and recurrent parotid carcinoma of the skull base which were all successfully retreated with high-activity 125iodine (I-125) permanent implantation.
We present the improved implant technique, intraoperative and postoperative complications, local control, and survival of 67 patients with cancer of the prostate treated by means of percutaneous transperineal template permanent 125iodine interstitial endocurietherapy (ECT). This ECT technique is a simple, easily learned, accurate and rapid procedure that can be performed without subjecting the patient to celiotomy. The use of vicryl carriers for permanent 125iodine implantation of the prostate with the percutaneous transperineal template technique prevents seed loss and permits implantation of patients after transurethral resection of the prostate (TURP).
The activities of ribulose bisphosphate carboxylase (RuBPC) and phosphoenolpyruvate carboxylase (PEPC), as indicators of autotrophic and nonautotrophic CO(2) fixation, were measured in excised cotyledons of Pinus radiata D. Don cultured for 21 days under shoot-forming (SF) and nonshoot-forming (NSF) conditions. The activity of RuBPC was found to increase in both SF and NSF cultures during the initial 5 days of culture. However, it leveled off from day 5 to day 10 and subsequently began to decrease until the end of the culture period under the SF conditions. In contrast, in the NSF cultures, RuBPC activity increased until day 15, when it was twofold higher than the maximum activity found in the SF cultures. An increase in PEPC activity of about 2.5 times the level of activity in freshly excised cotyledons was observed during the initial 5 days of culture under the SF conditions. PEPC activity began to decline after day 5 until it reached the level of activity seen in NSF cotyledons by day 15. In contrast, the activity of PEPC did not show any significant increase during the initial 10 days of culture under the NSF conditions. The K(m) (phosphoenolpyruvate) of PEPC from SF cotyledons was about 35% higher than that of NSF cotyledons. Cotyledons from two culture periods (days 5 and 15) were incubated for 15 seconds with NaH(14)CO(3). The label in the malate and asparatate fractions as a percentage of total (14)C incorporation was 3 times higher in the SF cotyledons than in the NSF cotyledons. A higher incorporation of (14)C into products of photosynthesis under the NSF conditions was also observed.
Using new 125I brachytherapy techniques, we were able to deliver safely a tumor volume dose of 16,000 rads to a previous irradiated, large, recurrent sacral chordoma by means of the intraoperative interstitial implantation of 229 low activity 125I seeds and 40,000 rads to a previously irradiated, small, recurrent clival chordoma by means of the transnasal needle implantation of two high activity 125I seeds. Iodine-125 brachytherapy was followed by regression of tumor, lessening of symptoms, and bony recalcification in both cases.
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Thirty-seven patients with previously untreated invasive carcinoma of the uterine cervix, International Federation of Gynecology and Obstetrics (FIGO) stages IB to IVA, were treated with 4,000 rad external beam radiotherapy (EXRT) to midplane, followed by two intracavitary endocurietherapy (ECT) applications of 2,500 rad each to point "A" using a Kumar applicator, for a total dose of 9,000 rad. The major complication rate was 2.7 percent, and the local control rate was 85 percent (22/26 patients) for stages IB and II, and 91 percent (10/11 patients) for stages III and IVA. The three-year uncorrected observed actuarial survival was 80.3 percent for stages IB and II, and 81.8 percent for stages III and IVA. The three-year adjusted actuarial survival rate was 95.2 percent for stages IB and II, and 90.5 percent for stages III and IVA.
Our technique for dual-field rotational total skin electron beam therapy (TSEBT) is described in detail. The need for boost to different sites due to self-shielding or artificial shielding is also described in detail.
The histopathology of two patients with radiation-induced neoplasms of the brain following therapeutic irradiation for intracranial malignancies is described. The second neoplasms were an atypical meningioma and a polymorphous cell sarcoma, respectively. They occurred 12 and 23 years after irradiation (4000 rad), within the original field of irradiation. In both cases, the radiation-induced tumors were histologically distinct from the initial medulloblastomas. Both patients were retreated with local irradiation using permanent implantation of radioactive iodine-125 seeds.
Retrospective analysis of 76 patients with locally advanced squamous cell carcinoma of multiple head and neck sites, who were treated by surgical resection and either 4,000-5,000, 6,000, or 6,600 rad postoperative external beam radiotherapy, revealed reduced local recurrence rates with increasing postoperative radiation dose.
Comparison of dosimetry measured in a noncylindrical Rando-Alderson phantom by two-field, four-field, and six-field total-skin electron-beam therapy (TSEBT) techniques with our dual-field rotational (DFR) technique reveals a superior dosimetry for the latter. Our technique of dual-field rotational DFR-TSEBT is described in detail, and its advantages and indications for the primary management of cutaneous T-cell lymphoma (CTCL) and Kaposi's sarcoma (KS) are discussed.
A rare, previously irradiated, recurrent malignant angioblastic meningioma of the pituitary, hemangiopericytic type, was locally controlled by a new endocurietherapy technique that allows delivery of very high (10,000 cGy), sharply localized irradiation. Rather than succumbing to the local tumor recurrence, as would otherwise be expected, the patient developed distant spinal metastases several years later.
An uncontrolled retrospective analysis of 76 patients with locally advanced Stage III and Stage IV squamous cell carcinoma of the oral cavity, oropharynx, pyriform sinus, supraglottic larynx, glottic larynx, and hypopharynx, who were treated in a uniform manner by surgical resection and 6,600 rad postoperative external beam radiotherapy, revealed relatively high 2-year and 4-year adjusted survival rates of 76% and 68%, respectively. Complication rates were acceptable (8%). The advantages of this treatment approach for locally advanced head and neck cancers compared to treatment by surgery alone are discussed.