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Biomedical subjects

R Grimshaw

Publications and source records attributed to R Grimshaw.

15 recordsLinked to original sources
PubMed2001

Epoetin alfa in cancer patients: evidence-based guidelines.

Anemia is a common cause of cancer-related fatigue. A systematic review of the literature was performed to establish guidelines on the use of epoetin alfa for the treatment of anemia. The evidence in support of these guidelines was selected, reviewed, and summarized by the members of the Canadian Cancer and Anemia Guidelines Development Group. The effects of epoetin alfa on quality of life (QOL) in patients with cancer were examined in 5 randomized, placebo-controlled trials and 2 large, open-label, nonrandomized, community-based studies. The effects of epoetin alfa on red blood cell transfusion requirements were examined in 19 randomized controlled trials (RCTs) with 21 comparisons. All trials compared epoetin alfa to a suitable control group, examined specified outcome measures that could be analyzed, and studied patients with cancer who were receiving chemotherapy. Trials involving patients with hematologic malignancies originating in the bone marrow were excluded. Outcome measures included 1) quality of life (QOL) (as measured by scales including the Linear Analogue Self-Assessment [LASA] and the Functional Assessment of Cancer Therapy [FACT] subscales), and 2) transfusion requirements (as measured by the proportion of patients requiring transfusion and amount of transfusion). The analysis confirmed that epoetin alfa produced statistically significant and clinically relevant improvements in QOL in patients with cancer. The overall relative risk ratio for transfusion among patients receiving epoetin alfa was calculated to be 0.60 (95% Cl, 0.53-0.69; P < 0.00001), representing a 40% reduction in the proportion of patients requiring transfusion. These results support recommendations for the use of epoetin alfa in patients with cancer-related anemia.

Anemia↗
PubMed2000

Phase II feasibility study of sequential couplets of Cisplatin/Topotecan followed by paclitaxel/cisplatin as primary treatment for advanced epithelial ovarian cancer: a National Cancer Institute of Canada Clinical Trials Group Study.

PURPOSE: Despite the improved results in advanced ovarian cancer achieved with the addition of paclitaxel to frontline therapy, there remains room for improvement. One approach is to add new agents such as topotecan. Because myelosuppression limits the delivery of topotecan with paclitaxel/cisplatin in a three-drug combination, we explored giving sequential couplets of cisplatin/topotecan followed by paclitaxel/cisplatin. PATIENTS AND METHODS: Forty-four patients with residual epithelial ovarian carcinoma after primary surgery were studied. Cisplatin 50 mg/m(2) on day 1 and topotecan 0.75 mg/m(2) on days 1 through 5 were administered at 21-day intervals for four cycles, followed by interval debulking surgery (if optimal debulking was not achieved with primary surgery), and then paclitaxel 135 mg/m(2) over 24 hours on day 1 and cisplatin 75 mg/m(2) on day 2 at 21-day intervals for four cycles. RESULTS: Such sequential couplets are feasible. Myelotoxicity was the major toxic effect, but it was of short duration. The granulocyte nadir with topotecan/cisplatin occurred late (median, day 18), so retreatment on day 21 was not always possible. There was no unexpected nonhematologic toxicity. The regimen was active in this group of patients who had undergone largely suboptimal debulking surgery. In 34 patients with clinically measurable disease, the overall response rate was 78%, and 30 (77%) of the 39 patients with elevated CA 125 levels at baseline had normalization of CA 125 levels by the end of therapy. CONCLUSION: Sequential couplets of cisplatin/topotecan followed by paclitaxel/cisplatin are feasible. The efficacy data in this suboptimal group of patients has encouraged us to proceed with a randomized study based on this approach.

Adult↗
PubMed2000

Randomized intergroup trial of cisplatin-paclitaxel versus cisplatin-cyclophosphamide in women with advanced epithelial ovarian cancer: three-year results.

BACKGROUND: A randomized trial conducted by the Gynecologic Oncology Group (GOG, study #111) in the United States showed a better outcome for patients with advanced ovarian cancer on the paclitaxel-cisplatin regimen than for those on a standard cyclophosphamide-cisplatin regimen. Before considering the paclitaxel-cisplatin regimen as the new "standard," a group of European and Canadian investigators planned a confirmatory phase III trial. METHODS: This intergroup trial recruited 680 patients with broader selection criteria than the GOG #111 study and administered paclitaxel as a 3-hour instead of a 24-hour infusion; progression-free survival was the primary end point. Patient survival was analyzed by use of the Kaplan-Meier technique. Treatment effects on patient survival were estimated by Cox proportional hazards regression models. All statistical tests were two-sided. RESULTS: The overall clinical response rate was 59% in the paclitaxel group and 45% in the cyclophosphamide group; the complete clinical remission rates were 41% and 27%, respectively; both differences were statistically significant (P =.01 for both). At a median follow-up of 38.5 months and despite a high rate of crossover (48%) from the cyclophosphamide arm to the paclitaxel arm at first detection of progression of disease, a longer progression-free survival (log-rank P =.0005; median of 15.5 months versus 11.5 months) and a longer overall survival (log-rank P =. 0016; median of 35.6 months versus 25.8 months) were seen in the paclitaxel regimen compared with the cyclophosphamide regimen. CONCLUSIONS: There is strong and confirmatory evidence from two large randomized phase III trials to support paclitaxel-cisplatin as the new standard regimen for treatment of patients with advanced ovarian cancer.

Adult↗
PubMed1999

Idoxifene antagonizes estradiol-dependent MCF-7 breast cancer xenograft growth through sustained induction of apoptosis.

Idoxifene is a novel selective estrogen (E2) receptor (ER) modulator that is currently in clinical development for the treatment of breast cancer. Compared to tamoxifen, idoxifene is metabolically more stable, with a higher relative binding affinity for the ER and reduced agonist activity on breast and uterine cells. Idoxifene also inhibits calmodulin, a calcium-binding protein that is involved in cell signal transduction pathways. In this study, the abilities of idoxifene and tamoxifen to antagonize E2-dependent MCF-7 xenograft growth in oophorectomized athymic mice were compared. The basis for idoxifene's antitumor activity was examined by comparing the effectiveness of the clinically used transisomer (referred to here as idoxifene) with its cis-isomer, which has a 50-fold lower relative binding affinity for ER than idoxifene but similar calmodulin-inhibitory activity. Changes in tumor cell proliferation, apoptosis, and ER-dependent protein expression were studied. Both idoxifene and tamoxifen significantly inhibited E2-dependent tumor growth, whereas cis-idoxifene had little effect. Withdrawal of E2 support induced significant tumor regression due to impaired cell proliferation (Ki-67 score, 9 versus 51% compared to E2 controls) and induction of apoptosis (3.6 versus 0.9% compared to E2 controls). Both anti-E2s inhibited cell proliferation and caused a significant 3-fold induction of apoptosis in E2 supported tumors after 1 week, which was maintained for 3 months with idoxifene (3.1 versus 0.48% compared to E2 controls) but decreased back to baseline in tumors treated with tamoxifen (0.69%). In contrast, cis-idoxifene had no effect on either cell proliferation or apoptosis. Both tamoxifen and idoxifene initially induced ER expression, whereas prolonged therapy with tamoxifen significantly reduced progesterone receptor levels. In conclusion, idoxifene resulted in similar inhibition of E2-dependent MCF-7 xenograft growth compared with tamoxifen, an effect that is mediated via ER rather than through calmodulin. Sustained induction of apoptosis may contribute to prolonged antagonism of E2-dependent growth, and it occurred to a greater extent following 3 months of idoxifene, compared to tamoxifen.

Adenocarcinoma↗
PubMed1999

Hamiltonian-versus-energy diagrams in soliton theory.

Parametric curves featuring Hamiltonian versus energy are useful in the theory of solitons in conservative nonintegrable systems with local nonlinearities. These curves can be constructed in various ways. We show here that it is possible to find the Hamiltonian (H) and energy (Q) for solitons of non-Kerr-law media with local nonlinearities without specific knowledge of the functional form of the soliton itself. More importantly, we show that the stability criterion for solitons can be formulated in terms of H and Q only. This allows us to derive all the essential properties of solitons based only on the concavity of the curve H vs Q. We give examples of these curves for various nonlinearity laws and show that they confirm the general principle. We also show that solitons of an unstable branch can transform into solitons of a stable branch by emitting small amplitude waves. As a result, we show that simple dynamics like the transformation of a soliton of an unstable branch into a soliton of a stable branch can also be predicted from the H-Q diagram.

Journal Article↗
PubMed1998

Randomized phase II study of two schedules of topotecan in previously treated patients with ovarian cancer: a National Cancer Institute of Canada Clinical Trials Group study.

PURPOSE: As topotecan is S-phase-specific, its efficacy is likely schedule-dependent. Therefore, a randomized study using a "pick the winner" design was undertaken to compare two schedules in patients with recurrent ovarian cancer. PATIENTS AND METHODS: Patients with recurrent epithelial ovarian cancer previously treated with no more than two separate regimens of chemotherapy, one of which had to be platinum-containing, were randomized to either topotecan 1.5 mg/m2 intravenously (i.v.) over 30 minutes daily for 5 days repeated every 21 days (arm A, the standard arm), or topotecan 1.75 mg/m2 as a 24-hour infusion once a week for 4 weeks repeated every 6 weeks (arm B, the experimental arm). RESULTS: Sixty-six patients were eligible and 63 were assessable for response. The response rate in arm A was 22.6% (95% confidence interval [CI], 9.6% to 41.2%), which was significantly superior to that in arm B, 3.1% (95% CI, 0.1% to 16%) (P = .026). The regimens were not equitoxic, with 94% of patients on arm A experiencing grade 3 or 4 granulocytopenia as opposed to 52% on arm B. CONCLUSION: The weekly 24 hour infusion of topotecan at 1.75 mg/m2 was ineffective in relapsed ovarian cancer. The daily-times-five schedule remains the schedule of choice. As the regimens were not equitoxic, one cannot differentiate between an ineffective schedule and an ineffective dose as the reason for the differing response rates. However, the degree of myelotoxicity that already occurs will preclude any substantially higher dosing with the weekly regimen.

Adolescent↗
PubMed1997

Antagonism of estrogen receptor and calmodulin association by antiestrogens is not dependent on an interaction with calmodulin.

Previously, two antiestrogens estradiol derivatives (3 and 4) bearing the basic side chain of tamoxifen were shown to impede the binding of the estrogen receptor (ER) to calmodulin (CaM)-Sepharose. In this study, the interaction of these and related compounds with calmodulin was examined using the cyclic AMP phosphodiesterase (cAMP-PDE) assay. Neither of the steroids gave any significant inhibition of the calmodulin dependent cAMP-PDE activity up to a final concentration of 20 microM. For comparison, tamoxifen and nafoxidine produced IC50 values of 6.7 microM +/- 1.0 and 7.4 microM +/- 1.1, respectively. In addition, a comparison was made of the activity of some triphenylethylene derivatives against CaM dependent cAMP-PDE and the ER-CaM Sepharose assays, but no relationship was observed. Overall, these results demonstrate that inhibition of the ER-CaM association by various steroidal and triphenylethylene antiestrogens does not relate to antagonism of calmodulin function or their binding affinity for the estrogen receptor.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1996

The control and biological importance of intratumoural aromatase in breast cancer.

The existence of aromatase activity in human breast carcinomas has been established for about 20 years but the clinical and biological importance of this remains unclear. A number of studies in clinical material suggest that aromatase activity may be a prerequisite of response to aromatase inhibitors and that aromatase activity may be enhanced in those tumours relapsing during treatment with one such inhibitor, aminoglutethimide. These results would carry more significance, however, if it was demonstrable that the growth of breast carcinomas is affected by the conversion of androgens to oestrogens by intratumoural aromatase. We have tried to address this by establishing model systems with aromatase-transfected MCF7 breast cancer cells. We have demonstrated that these cells can be stimulated mitogenically with androgen and that this proliferation is suppressible with aromatase inhibitors. Similarly the growth of aromatase transfected cells but not wild type cells as xenografts is supported by androstenedione and inhibitable by both the steroidal aromatase inhibitor, 4-hydroxyandrostenedione and non-steroidal inhibitor, CGS 20267. Work with the former of these, which is a suicide inhibitor allowed us to demonstrate that growth can proceed with aromatase activity approximating to the highest level seen in breast carcinomas indicating that at least at this extreme level the intratumoural conversion of androgens to oestrogens may indeed be able to support tumour growth. Further work with this mode system should allow us to define the minimal amount of intratumoural activity which can support tumour growth.

Adenocarcinoma↗
PubMed1996

Oestrogen formation in breast: clinical and biological importance.

It has been known for many years that many breast carcinomas can synthesize oestrogens from androgens via the action of the enzyme aromatase. There has been widespread speculation on the possibility that this acts as an important intracrine source of growth stimulation. For example, there are data which indicate that clinical response to aromatase inhibitors is far more common in tumours which possess measurable amounts of aromatase. In addition, aromatase activity in the quadrant of the normal breast surrounding breast carcinomas is generally higher than in the other quadrants. However, these data are only suggestive and the case for a significant role for intratumoural aromatase in breast cancer growth remains unproven. We have recently explored this possibility by the transfection of human breast cancer cells with aromatase. By a series of experiments in athymic mice we have demonstrated that growth is supported by this intracrine source in the absence of endocrine oestrogen stimulation.

Androstenedione↗
PubMed1994

Evidence that tamoxifen binds to calmodulin in a conformation different to that when binding to estrogen receptors, through structure-activity study on ring-fused analogues.

A ring-fused analogue of tamoxifen, which had previously been shown to have practically identical estrogen receptor (ER) affinity and antitumour potency against estrogen responsive cells as tamoxifen, failed to inhibit calmodulin-dependent cyclic AMP phosphodiesterase. The substitution of an extra methyl group into the ring-fused analogue, at a position which the ethyl group of tamoxifen can occupy in one of its conformations, restored the calmodulin inhibition. Also, the replacement of the tamoxifen ethyl group by methyl diminishes calmodulin inhibition. Direct interaction of these tamoxifen analogues with calmodulin was demonstrated through the use of the fluorescent probe, 2-p-toluidinyl-naphthalene-6-sulfonic acid (TNS). These findings lead to the conclusion that tamoxifen binds to calmodulin in a conformation not accessible to the fused analogue and therefore likely to be different to that which binds to the ER. Also, the results on the ring-fused analogues indicate that the calmodulin binding cannot be essential for antitumour activity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

When two souls meet.

As a nurse specialist working in a regional gender identity unit, Rosemary Grimshaw is frequently called on for advice. Here she describes her role and some common misconceptions about transsexualism.

Adult↗