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Biomedical subjects

N R Datta

Publications and source records attributed to N R Datta.

At least 19 recordsLinked to original sources
PubMed2006

Does the evidence support the use of concurrent chemoradiotherapy as a standard in the management of locally advanced cancer of the cervix, especially in developing countries?

Locally advanced cancer of the cervix (FIGO stages III and IVA) is one of the most common malignancies in developing countries. Conventional treatment has been a judicious combination of external radiotherapy and intracavitary brachytherapy. However, prompted by the results of five randomised-controlled trials (RCTs) published in close succession, The National Cancer Institute (NCI) alert in 1999, and two meta-analyses, the management of cancer of the cervix has gradually changed. Concurrent chemoradiotherapy with cisplatin alone, or in combination, is gradually being favoured for the treatment of cancer of the cervix. This overview examines whether the published evidence is sufficiently adequate to justify the use of chemoradiotherapy using cisplatin as standard care in the management of cancer of the cervix, especially in developing countries, where most women present with locally advanced cancer of the cervix. A critical review of the various phase III randomised trials and meta-analyses indicates that, although chemoradiotherapy could be a standard form of treatment for early cancer of the cervix, its role in advanced stages needs further exploration before this could be incorporated into routine clinical care.

Combined Modality Therapy↗
PubMed2005

An audit of postoperative radiotherapy after non-curative resection for cancer of the oesophagus.

AIMS: The role of postoperative radiotherapy (PORT) after non-curative resections for cancer oesophagus is not well defined. A policy of offering PORT after non-curative resections for cancer oesophagus has been followed at our institution, and we report an audit of our experience. MATERIAL AND METHODS: Between March 1990 and September 2002, 139 patients underwent resections for cancer oesophagus. Of these, 86 patients received PORT to a dose of 45-50.4 Gy/25-28 fractions. Eleven of these patients also received concurrent and adjuvant 5-fluorouracil (5-FU). Disease-free survival and overall survival were computed from the day of surgery using the Kaplan-Meier method. RESULTS: Seventy-six per cent (65/86) of patients had squamous cell carcinoma and 69% (59/86) of patients had tumours in the lower-third of the oesophagus. The median interval between surgery and PORT was 41 days, and 93% of patients received doses as planned. Strictures at the anastomotic site and ulcerations in the stomach mucosa were seen in 17% and 5% of patients, respectively. The median and 5-year disease-free survival was 12 months (95% CI 9.9-14.1) and 14%; whereas the median and 5-year overall survival was 17 months (95% CI 12.4-21.6) and 17%, respectively. Local and distant failures were seen in 29% and 45% of patients, respectively. CONCLUSIONS: PORT, after a non-curative resection of cancer oesophagus, is well tolerated with acceptable morbidity and survival.

Adenocarcinoma↗
PubMed2004

Problems and uncertainties with multiple point A's during multiple high-dose-rate intracavitary brachytherapy in carcinoma of the cervix.

AIMS: This study evaluates the consequences of point A as a dose prescription point during multiple high-dose-rate (HDR) intracavitary brachytherapy (ICBT) in cancer cervix. MATERIALS AND METHODS: Fifty patients who had received teletherapy were randomised into two groups of 25 to receive three HDR ICBT fractions of 6 Gy each at point A with either a flexible Ralstron (Shimadzu Corporation, Japan) or rigid Rotterdam (Nucletron, Netherlands) applicator. The orthogonal radiographs of the 150 applications were evaluated for applicator geometry and point A co-ordinates. RESULTS: Irrespective of the nature and rigidity of the applicators, its various components exhibited a highly significant variation during multiple fractionated HDR ICBT. The Cartesian co-ordinates of point A (left and right) for the applicator geometry also showed significant variation during multiple HDR ICBT procedures. This resulted in an average shift of 9.5 mm (SD= +/-4.4) and 11.1 mm (SD= +/-6.4) in right point A, 10.2 mm (SD= +/-4.5) and 10.8 mm (SD= +/-6.6) in left point A for Ralstron and Rotterdam applicator, respectively, during the three HDR ICBT. Consequently, doses to both right and left point A's showed significant variation during multiple ICBT application and were independent of the applicator type. CONCLUSION: Applicator variation in the components and spatial position in the pelvis during multiple HDR ICBT results in multiple point A's irrespective of the nature of applicator, leading to uncertainty in the dose prescription. These uncertainties, which have a bearing on clinical end points, could be minimised by shifting from point-based dose prescription to image-based target localisation and treatment planning in ICBT.

Adult↗
PubMed2004

Predictors of survival end points in patients with cancer of the cervix on long-term follow-up: inferences and implications from an audit of patients treated with a specific radiotherapy protocol.

AIMS: An audit of patients with cancer of the cervix treated with a specified protocol of external beam radiotherapy (EXRT) followed by intracavitary brachytherapy (ICBT) was carried out to determine the prognosticators for major survival end points. MATERIALS AND METHODS: Patients treated between 1991 and 2003 with a uniform protocol of EXRT (50 Gy/25 fractions/5 weeks) followed by high-dose-rate ICBT (18 Gy/3 fractions/3 weeks) were selected from the database. Various clinical and treatment parameters were evaluated for extent of locoregional response at completion of EXRT, namely absence or presence of gross residual tumour (AGRT and PGRT, respectively) and survival end points. These included locoregional disease-free survival (LDFS), disease-free survival (DFS) and overall survival (OS). RESULTS: Of the 157 evaluable patients, 145 (92%) belonged to FIGO stages II and III. Eighty-three (53%) at completion of EXRT had AGRT, which was influenced by age and gross tumour features. The estimated 10-year LDFS, DFS and OS were 38.6%, 33.1% and 38.5%, respectively. Factors significant on univariate analysis for these survival end points were EXRT duration, ICBT time, overall treatment time (OTT) and EXRT response. On multivariate analysis, AGRT to EXRT, an OTT of < or = 67 days, and patients older than 50 years were the significant favourable determinants for all the above survival end points. CONCLUSION: The audit highlights that younger people, especially those with bulky tumours that determine response to EXRT, are poor prognosticators for survival end points. They could perhaps benefit from treatment intensification regimens using chemoradiotherapy, provided that OTT is not unduly prolonged.

Adult↗
PubMed2004

Postoperative residual tumour imaged by contrast-enhanced computed tomography and 201Tl single photon emission tomography: can they predict progression-free survival in high-grade gliomas?

AIMS: To evaluate if postoperative residual tumour imaged by either computed tomography or 201Tl single photon emission tomography (SPECT) carried out postoperatively could predict progression-free survival (PFS) in high-grade malignant gliomas. MATERIALS AND METHODS: Thirty-three patients with high-grade malignant gliomas underwent both contrast-enhanced CT scan and 201Tl-SPECT postoperatively before receiving radiotherapy. The PFS was evaluated against the individual reports of the above two imaging studies by univariate analysis. RESULTS: CT and 201Tl-SPECT were carried out within a median interval of 17 days after surgery. Of the 33 patients, CT and 201Tl-SPECT were reported as positive for residual tumours in 23 (69.7%) and 30 (91%) patients, respectively. Sensitivity, specificity and overall accuracy were 71.4%, 40% and 66.6% for CT, and 96.4%, 40% and 87.8% for 201Tl-SPECT, respectively, and were based on their last follow-up status (P = 0.627 for CT; P = 0.053 for 201Tl-SPECT). The median PFS for patients reported to be positive or negative on CT scan was 4 and 5 months, respectively (P = 0.202). With 201Tl-SPECT, although the median PFS for patients with a positive 201Tl uptake was also 4 months, it had not even reached for those reported having a negative 201Tl uptake (cumulative survival 66.7% at last follow-up) (P = 0.198). However, Karnofsky performance status (KPS) was the only significant predictor on univariate analysis (KPS: < 80 vs. > or = 80; P < 0.001) for PFS. CONCLUSIONS: Although both the imaging modalities have a poor specificity, postoperative 201Tl-SPECT had a significantly better accuracy to predict the status at last follow-up than contrast-enhanced CT. Nevertheless, KPS remained the most significant outcome predictor for PFS in high-grade malignant gliomas.

Adult↗
PubMed2003

Multimodality image fusion in dose escalation studies of brain tumors.

This article examines the utility of integrating images from computed tomography (CT), magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT) for radiation treatment planning of brain tumors for dose escalation studies. The information obtained from these imaging modalities is complementary to each other and could provide anatomic (through CT and MRI) and metabolic (through SPECT) information of the target. This anato-metabolic target localization could be expected to facilitate precise radiation therapy planning for brain tumors by delineating the boundary between the tumor, edema, and the normal brain parenchyma and identify the viable tumor nidus with greater degree of certainty. This could in turn lead to minimize dose to the normal tissue and permit dose escalation to the region of interest. The utility of these anato-metabolic imaging modalities for defining the clinical target volumes along with planning target volumes for different phases of the radiation therapy is illustrated.

Adult↗
PubMed2002

Electron beam therapy at extended SSDs: an analysis of output correction factors for a Mitsubishi linear accelerator.

The effects of extended source-to-surface distance (SSD) on the electron beam dose profiles were evaluated for various electron beam energies--6, 9, 12, 15 and 20 MeV-and the accuracy of various output correction methods was analysed on a Mitsubishi linear accelerator using a radiation field analyser (RFA). The dose fall-off region of the central axis depth-dose curves was nearly independent for SSDs up to 120 cm where as in the build-up region, a marginal reduction of surface dose was observed, particularly for lower energies and for smaller field sizes. Effective SSDs and virtual source distances were evaluated for field sizes ranging from 5 x 5 to 15 x 15 cm2 for various energies. Curve fitting was done with the measured outputs with various equations and coefficients were evaluated. The accuracy of the derived output correction factors by effective SSD, virtual source distance and curve-fit methods was assessed by evaluating correlation coefficients between the calculated and the measured values. The correlation coefficient was best with the linear-quadratic equation followed by the effective SSD method and the virtual source method. The output correction based on the linear-quadratic equation showed the best estimate of electron beam output at extended SSDs with an accuracy well within +/- 1%. The rapid reduction of dose due to the applicator-scattered component at d(max) point with an extended SSD was significant for the 5 x 5 cm2 applicator and lower energies.

Algorithms↗
PubMed2001

Variations of intracavitary applicator geometry during multiple HDR brachytherapy insertions in carcinoma cervix and its influence on reporting as per ICRU report 38.

PURPOSE: This paper examines the extent of variation in the applicator geometry during multiple high dose rate (HDR) intracavitary brachytherapy (ICBT) applications and its impact on reporting as per ICRU report 38. MATERIALS AND METHODS: Eighty orthogonal radiographs from 20 consecutive patients of carcinoma cervix (FIGO stages, IIA-IIIB) having four HDR ICBT applications of 6 Gy each at weekly intervals following teletherapy were evaluated. The applicator consisted of a flexible intrauterine tandem (IUT) independent of the ovoid assembly. The applicator geometry was evaluated in terms of: alpha angle, beta angle, intrauterine length (IUTL), interovoid (IOV), os to right ovoid (ORT) and os to left ovoid (OLT) distances along with vertical (VDL) and anteroposterior displacements (ADL) of the os with respect to the ovoids. The Cartesian co-ordinates (X, Y, and Z) of the IUT tip, centre of both ovoids and os were also measured. Doses to right point A (ARD), left point A (ALD), along with a reference volume of 6 Gy for ICRU height (IRH), width (IRW), thickness (IRT) and volume (IRV) were estimated for each application. RESULTS: Highly significant differences (P<0.001) between four insertions in any given patient across 20 patients for alpha angle, beta angle, IUTL, IOV, ORT, VDL, co-ordinates of the IUT, ovoids and os were observed, except for ADL (P=0.041) and OLT (P=0.247). As a consequence, variations were observed in ARD (P=0.027), ALD (P=0.017); IRH, IRW, IRT and IRV (all P<0.001). Applicator factors which influenced the various dose specification parameters were: beta angle and ORT for both ARD and ALD; UTLN, VDL and ORT for IRH; UTLN and IOV for IRW; UTLN for IRT and VDL for the 6 Gy IRV. CONCLUSIONS: A significant variation of the applicator geometry and its movement was observed in patients undergoing multiple HDR ICBT. This could have implications for reporting dose and volume specifications as required by ICRU report 38.

Brachytherapy↗
PubMed2001

Squamous cell carcinoma arising from a congenital duplication cyst of the esophagus in a young adult.

Squamous cell carcinomas arising from the congenital anomalies in the esophagus are rare. One such case of an 18-year-old man, with an associated history of ventricular septal defect, who developed an epithelial malignancy within the duplication cyst extending to involve the lower third of esophagus is presented here. He responded well to radical treatment using concurrent chemo-irradiation, and continues to be free of disease after a follow-up of 14 months.

Abnormalities, Multiple↗
PubMed2000

Biological integral dose: an alternate method for numerical scoring of rival plans.

Numerical scoring of rival plans (NSRP) are usually based either on basis of dose-volume histograms (DVH) or the relative values of corresponding normal tissue complication probabilities (NTCP) and tumor control probabilities (TCP). An alternative method for NSRP based on biological integral dose (BID) is being proposed, which is illustrated using a case of pituitary tumor planned to receive a dose of 50 Gy in 25 fractions over 5 weeks. BID for the various alternate plans -2-field (2F), 3-field (3F), 220 degrees arc (ARC) and 3-field static multileaf collimator (MLC) were calculated using the integration of the product of extrapolated response dose and the corresponding mass of the tissue enclosed separately for tumor and the normal brain in the entire planned target volume or a selected range of dose (approximately 90% and above of the normalized dose). Ratios of the BID for the brain versus the tumor were obtained and the plans were ranked on the basis of the least value of this ratio. In all of these plans, although the DVHs for normal brain were different, the DVHs for tumor were almost identical. However, the BID values for brain for 2F, 3F, ARC, and MLC were 22.53 Joules (J), 21.176 J, 21.991 J, and 10.608 J, respectively, and for tumor 0.561 J, 0.552 J, 0.555 J, and 0.556 J, respectively. The corresponding brain/tumor values were 40.16 (2F), 38.36 (3F), 39.62 (ARC), and 19.08 (MLC), thus ranking the plans in order of merit as MLC, 3F, ARC, and 2F. The BID for volumes encompassed by 90% and more of the normalized dose magnified the differences between the plans, with 2F being 29.99, compared to 3.82 for MLC. Rankings of rival plans could be based on the concept of BID. It requires a lesser number of uncertain variables and therefore could be used as an alternative technique in evaluation of the different plans in routine clinical practice.

Humans↗
PubMed2000

Primary CNS lymphoma: an audit of cases treated over a nine year period and review of the literature.

Primary CNS lymphoma is a rare tumor comprising around one percent of all brain tumors. This report is an audit of eight cases [5 males, 3 females, age range: 17-55 years] which were accrued over nine years. All patients underwent surgical decompression, followed by radical Radiotherapy [RT]. Five out of eight patients received adjuvant chemotherapy in the form of CHOP or PCV. Of the patients who relapsed two received CHOP as a salvage therapy, one received PCV therapy and lomustine with intrathecal methotrexate. At a median follow up of 16 months [range 1 to 39 months] the two year disease free survival and overall survival were 13 percent and 38 percent respectively, which is in accordance with the literature. High dose RT to whole skull with boost therapy is indicated for all the cases. However, the role of chemotherapy and the appropriate regime needs to be defined with certainty.

Adolescent↗
PubMed1999

Carcinoma of the penis metastasizing to the dorsal spine. A case report.

Carcinoma of the penis tends to have a predictable route of spread by direct invasion and by regional lymphatic involvement to the inguinal group of lymph nodes. Blood-borne distant spread is rare, last to occur, and is seen in 1-3% of cases. Metastasis to the spine is even rarer. We encountered one such case who presented with spinal metastasis, as documented by the whole body bone scan, and this was later followed by involvement of the inguinal nodes. This case is unique in its site of metastatic presentation as well as its pattern of presentation.

Aged↗
PubMed1999

Adjuvant therapy in invasive thymoma: an audit of cases treated over an 8 year period.

Invasive thymomas comprise 0.1%-0.2% of all malignancies in India. This report is an audit of 11 cases (10 males and 1 female) at a mean age of 36.6 years (range 25-52 years) of invasive thymoma accrued over an eight year period treated by combined modality treatment. Nine of these presented with myaesthenia gravis. All patients underwent initial surgery (3 partial and 8 total resections) and postoperative radiotherapy. Two of the three partially resected patients received one course of chemotherapy prior to radiotherapy consisting of cyclophosphamide, vincristine, procarbazine and prednisolone. At a median follow up of 28 months (range 2-87) there have been no local relapses, one distant metastasis and one death due to uncontrolled myaesthenia. The treatment strategies with invasive thymomas would depend upon the extent of resection. Postoperative radiotherapy appears to be indicated in all cases, however the role of chemotherapy may be limited to those with partial resection.

Adult↗