Epidermal growth factor receptor inhibitor-induced hypomagnesemia: a survey of practice patterns among Canadian gastrointestinal medical oncologists

Background

The optimal management of hypomagnesemia (hMg) induced by epidermal growth factor receptor inhibitors (egfris) for advanced colorectal cancer is unclear. We surveyed gastrointestinal medical oncologists in Canada to determine practice patterns for the management of egfri-induced hMg.

Methods

Based on distribution lists from the Eastern Canadian Colorectal Cancer Consensus Conference and the Western Canadian Gastrointestinal Cancer Consensus Conference, medical oncologists were invited to participate in an online questionnaire between November 2013 and February 2014.

Results

From the 104 eligible physicians, 40 responses were obtained (38.5%). Panitumumab was more commonly prescribed than cetuximab by 70% of respondents, with 25% prescribing cetuximab and panitumumab equally. Most respondents obtain a serum magnesium level before initiating a patient on an egfri (92.5%) and before every treatment (90%). Most use a reactive strategy for magnesium supplementation (90%) and, when using supplementation, favour intravenous (iv) alone (40%) or iv and oral (45%) dosing. Magnesium sulfate was used for iv replacement, and the most common oral strategies were magnesium oxide (36.4%) and magnesium rougier (18.2%). Under the reactive strategy, intervention occurred at hMg grade 1 (70.3%) or grade 2 (27%). Of the survey respondents, 45% felt that 1-5 of their patients have ever developed symptoms attributable to hMg, and 35% have had to interrupt egfri therapy because of this toxicity, most commonly at grade 3 (30%) or grade 4 (45%) hMg. The most important question about egfri-induced hMg was its relevance to clinical outcomes (45%) and its symptoms (37.5%).

Conclusions

In Canada, various strategies are used in the management of egfri-induced hMg, including prophylactic and reactive approaches that incorporate iv, oral, or a combination of iv and oral supplementation. Clinicians are concerned about the effect of hMg on clinical outcomes and about the symptoms that patients experience as a result of this toxicity.

What is a clinically meaningful survival benefit in refractory metastatic colorectal cancer?

Assessment of the clinical benefit of cancer treatments can be highly subjective, influenced by both perspective and context. Such assessments are required in regulatory and policy decision-making, but consistency between jurisdictions is often lacking. Clear and consistent standards for determining when a treatment offers a meaningful benefit, relative to the current standard of care, can help to address issues of equity and transparency in health technology assessment. For metastatic colorectal cancer (mcrc), no standardized Canadian definition of clinically meaningful benefit has yet been proposed. Colorectal Cancer Canada therefore convened a group of medical oncologists expert in colorectal cancer to review the literature about clinical significance. The resulting consensus is intended to apply to any therapeutic agent being considered in the setting of chemotherapy-refractory mcrc. It was agreed that overall survival is the appropriate measure of clinical efficacy in chemorefractory mcrc. As quantitative targets for efficacy, an improvement of 2 months or more in median overall survival or a hazard ratio for survival of 0.75 or lower (or both) are proposed as the threshold for clinically meaningful benefit. That threshold could be influenced by a treatment's effect on quality of life. Treatment toxicity is also relevant to the assessment of clinical benefit in this setting, specifically when significant differences in treatment tolerability are evident.

Abstract P6-17-29: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Veitch ZW, Bedard P, Tang PA, Conway JL, Ribnikar D, Albaba H, King K, Lupichuk S, Cescon D. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-29.

Opportunity is the greatest barrier to providing palliative care to advanced colorectal cancer patients: a survey of oncology clinicians

Palliative care (pc) is part of the recommended standard of care for patients with advanced cancer. Nevertheless, delivery of pc is inconsistent. Patients who could benefit from pc services are often referred late-or not at all. In planning for improvements to oncology pc practice in our health care system, we sought to identify barriers to the provision of earlier pc, as perceived by health care providers managing patients with metastatic colorectal cancer (mcrc). We used the Michie Theoretical Domains Framework (tdf) and Behaviour Change Wheel (bcw), together with knowledge of previously identified barriers, to develop a 31-question survey. The survey was distributed by e-mail to mcrc health care providers, including physicians, nurses, and allied staff. Responses were obtained from 57 providers (40% response rate). The most frequently cited barriers were opportunity-related-specifically, lack of time, of clinic space for consultations, and of access to specialist pc staff or services. Qualitative responses revealed that resource limitations varied by cancer centre location. In urban centres, time and space were key barriers. In rural areas, access to specialist pc was the main limiter. Self-perceived capability to manage pc needs was a barrier for 40% of physicians and 30% of nurses. Motivation was the greatest facilitator, with 89% of clinicians perceiving that patients benefit from pc. Based on the Michie tdf and bcw model, interventions that best address the identified barriers are enablement and environmental restructuring. Those findings are informing the development of an intervention plan to improve oncology pc practices in a publicly funded health care system.

Abstract P5-20-12: Adjuvant DCH vs TCH for low-risk (node negative); and FECDH vs TCH for high-risk (node positive) HER2+ breast cancer – A retrospective provincial analysis

Background: Chemotherapy plus trastuzumab for early HER2+ breast cancer (BC) is associated with improved survival. Optimal regimens for low-risk (node negative) and high-risk (node positive) HER2+ breast cancers are unknown and choice of regimen varies in real-world clinical practice.

Objective: (1) For low-risk breast cancer, to compare DCH (4 cycles) and TCH (6 cycles) in terms of disease free (DFS) and overall survival (OS). (2) For high-risk breast cancer, to compare FECDH (6 cycles) and TCH (6 cycles) in terms of DFS and OS.

Methods: All women diagnosed from 2007-2014 with stage I-III, hormone receptor (HR) +/-, HER2+ BC receiving adjuvant chemotherapy plus trastuzumab (n=986) in Alberta, Canada were included. Patients with low-risk (node negative) disease were stratified into DCH (n=104) or TCH (n=360) cohorts for DFS/OS comparison (Kaplan-Meier). Patients with high-risk (node positive) disease were stratified into FECDH (n=145) or TCH (n=314) cohorts. Subgroup analysis of the high-risk cohorts by HR+/HER2+ and HR-/HER2+ for FECDH vs TCH were performed. Chi-square was used to evaluate for difference between cohort variables.

Low- Risk Cohort DCH TCH  n (104)%n (360)%Age (mean)55.3 53.0 Hormone Status    ER+ or PR+8682.727676.7ER and PR-1817.38423.3Grade    121.951.423230.88523.637067.327075.0Surgery    lumpectomy525010830.5mastectomy525024669.5

High-Risk Cohort FECDH TCH  n (145)%n (314)%Age (mean)50.2 53.6 Hormone Status    ER+ or PR+11579.323875.8ER and PR-3020.77624.2Grade    10051.6229206119.631168014678.8Surgery    lumpectomy3927.19831.2mastectomy10572.921668.8Node Status    N18357.219461.8N24128.37323.2N32114.54715

Results: Median follow-up was 58.1 months in the low-risk cohort and 63.1 months in the high-risk cohort. In the low-risk group, patients receiving TCH had more mastectomy (69.5%) than lumpectomy (30.5%; p<0.001) compared to those receiving DCH (50%; 50%). No significant difference was seen in DFS (p=0.153) or OS (p=0.409) for patients in the DCH (92.3%; 95.2%) vs TCH (95.2%; 96.9%) cohorts. In the high-risk group, no significant difference was seen in DFS (p=0.226) or OS (p=0.164) for FECDH (92.4; 95.2%) or TCH (88.5%; 91.4%) respectively. In subgroup analysis of high-risk HR+/HER2+ BC, patients receiving FECDH demonstrated superior OS (98.3%; p=0.014) and a trend towards superior DFS (94.8%; p=0.069) relative to TCH patients (OS = 91.6%; DFS= 88.7%). Conversely, analysis of high-risk HR-/HER2+ BC, patients demonstrated higher DFS and OS for TCH (88.2%; 90.8%) relative to FECDH (83.3%; 83.3%); although this was non-significant (p=0.516; p=0.298) and likely underpowered. Nodal status was balanced between all groups (p=0.602).

Conclusion: In low-risk HER2+ BC, 4 cycles of DCH chemotherapy has high survival with similar outcomes to 6 cycles of TCH. In high-risk HER2+ BC, FECDH has comparable outcomes to TCH consistent with BCIRG-006. This study suggests that women with HR+/HER2+ breast cancer have improved OS with anthracycline containing regimens, such as FECDH. Although non-significant, patients with HR-/HER2+ BC may have some improvement in DFS and OS with TCH, a carboplatin containing regimen.

Citation Format: Veitch ZW, Khan OF, Tilley D, Kostaras X, Tang PA, King K, Lupichuk S. Adjuvant DCH vs TCH for low-risk (node negative); and FECDH vs TCH for high-risk (node positive) HER2+ breast cancer – A retrospective provincial analysis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-20-12.

Risk and predictors of suicide in colorectal cancer patients: a Surveillance, Epidemiology, and End Results analysis

Background

The risk of suicide is higher for patients with colorectal cancer (crc) than for the general population. Given known differences in morbidity and sites of recurrence, we sought to compare the predictors of suicide for patients with colon cancer and with rectal cancer.

Methods

Using the U.S. Surveillance, Epidemiology, and End Results database, adult patients with confirmed adenocarcinoma of the colon or rectum during 1973-2009 were identified. Parametric and nonparametric tests were used to assess selected variables, and Cox proportional hazards regression models were used to determine predictors of suicide.

Results

The database identified 187,996 patients with rectal cancer and 443,368 with colon cancer. Compared with the rectal cancer group, the colon cancer group was older (median age: 70 years vs. 67 years; p < 0.001) and included more women (51% vs. 43%, p < 0.001). Suicide rates were similar in the colon and rectal cancer groups [611 (0.14%) vs. 337 (0.18%), p < 0.001]. On univariate analysis, rectal cancer was a predictor of suicide [hazard ratio (hr): 1.26; 95% confidence interval (ci): 1.10 to 1.43]. However, after adjusting for clinical and pathology factors, rectal cancer was not a predictor of suicide (hr: 1.05; 95% ci: 0.83 to 1.33). In the colon cancer cohort, independent predictors of suicide included older age, male sex, white race, and lack of primary resection. The aforementioned predictors, plus metastatic disease, similarly predicted suicide in the rectal cancer cohort.

Conclusions

The suicide risk in crc patients is low (<0.2%), and no difference was found based on location of the primary tumour. Sex, age, race, distant spread of disease, and intact primary tumour were the main predictors of suicide among crc patients. Further studies and interventions are needed to target these high-risk groups.

Randomized phase II study of modified FOLFOX-6 in combination with ramucirumab or icrucumab as second-line therapy in patients with metastatic colorectal cancer after disease progression on first-line irinotecan-based therapy

BACKGROUND

Icrucumab and ramucirumab are recombinant human IgG1 monoclonal antibodies that bind VEGF receptors 1 and 2 (VEGFR-1 and -2), respectively. This randomized phase II study evaluated the antitumor activity and safety of icrucumab and ramucirumab each in combination with mFOLFOX-6 in patients with metastatic colorectal cancer after disease progression on first-line therapy with a fluoropyrimidine and irinotecan.

PATIENTS AND METHODS

Eligible patients were randomly assigned to receive mFOLFOX-6 alone (mFOLFOX-6) or in combination with ramucirumab 8 mg/kg IV (RAM+mFOLFOX-6) or icrucumab 15 mg/kg IV (ICR+mFOLFOX-6) every 2 weeks. Randomization was stratified by prior bevacizumab therapy. The primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS), tumor response, safety, and PK.

RESULTS

In total, 158 patients were randomized, but only 153 received treatment (49 on mFOLFOX-6, 52 on RAM+mFOLFOX-6, and 52 on ICR+mFOLFOX-6). Median PFS was 18.4 weeks on mFOLFOX-6, 21.4 weeks on RAM+mFOLFOX-6, and 15.9 weeks on ICR+mFOLFOX-6 (RAM+mFOLFOX-6 versus mFOLFOX-6, stratified hazard ratio [HR] 1.116 [95% CI 0.713-1.745], P = 0.623; ICR+mFOLFOX-6 versus mFOLFOX-6, stratified HR 1.603 [95% CI 1.011-2.543], P = 0.044). Median survival was 53.6 weeks on mFOLFOX-6, 41.7 weeks on RAM+mFOLFOX-6, and 42.0 weeks on ICR+mFOLFOX-6. The most frequent adverse events reported on the ramucirumab arm (RAM+mFOLFOX-6) were fatigue, nausea, and peripheral sensory neuropathy; those on the icrucumab arm (ICR+mFOLFOX-6) were fatigue, diarrhea, and peripheral sensory neuropathy. Grade ≥3 serious adverse events occurred at comparable frequency across arms.

CONCLUSIONS

In this study population, combining ramucirumab or icrucumab with mFOLFOX-6 did not achieve the predetermined improvement in PFS.

CLINICALTRIALSGOV

NCT01111604.

Estimation of drug cost avoidance and pathology cost avoidance through participation in NCIC Clinical Trials Group phase III clinical trials in Canada

BACKGROUND

Cost avoidance occurs when, because of provision of a drug therapy [drug cost avoidance (dca)] or a pathology test [pathology cost avoidance (pca)] during trial participation, health care payers need not pay for standard treatments or testing. The aim of our study was to estimate the total dca and pca for Canadian patients enrolled in relevant phase iii trials conducted by the ncic Clinical Trials Group.

METHODS

Phase iii trials that had completed accrual and resulted in dca or pca were identified. The pca was calculated based on the number of patients screened and the test cost. The dca was estimated based on patients randomized, the protocol dosing regimen, drug cost, median dose intensity, and median duration of therapy. Costs are presented in Canadian dollars. No adjustment was made for inflation.

RESULTS

From 1999 to 2011, 4 trials (1479 patients) resulted in pca and 17 trials (3195 patients) resulted in dca. The total pca was estimated at $4,194,849, which included testing for KRAS ($141,058), microsatellite instability ($18,600), and 21-gene recurrence score ($4,035,191). The total dca was estimated at $27,952,512, of which targeted therapy constituted 43% (five trials). The combined pca and dca was $32,147,361.

CONCLUSIONS

Over the study period, trials conducted by the ncic Clinical Trials Group resulted in total cost avoidance (pca and dca) of approximately $7,518 per patient. Although not all trials lead to cost avoidance, such savings should be taken account when the financial impact of conducting clinical research is being considered.

A phase II study of erlotinib in gemcitabine refractory advanced pancreatic cancer

BACKGROUND

Erlotinib induced skin toxicity has been associated with clinical benefit in several tumour types. This phase II study evaluated the efficacy of erlotinib, dose escalated to rash, in patients with advanced pancreatic cancer previously treated with gemcitabine.

METHODS

Erlotinib was given at an initial dose of 150 mg/day, and the dose was escalated by 50mg every 2 weeks (to a maximum of 300 mg/day) until >grade 1 rash or other dose limiting toxicities occurred. Erlotinib pharmacokinetics were performed, and baseline tumour tissue was collected for mutational analysis and epidermal growth factor receptor (EGFR) expression. The primary end-point was the disease control rate (objective response and stable disease >8 weeks).

RESULTS

Fifty-one patients were accrued, and 49 received treatment. Dose-escalation to 200-300 mg of erlotinib was possible in 9/49 (18%) patients. The most common ⩾ grade 3 adverse events included fatigue (6%), rash (4%) and diarrhoea (4%). Thirty-seven patients were evaluable for response, and the best response was stable disease in 12 patients (32% (95% confidence interval (CI) 17-47%)). Disease control was observed in nine patients (24% (95% CI: 10-38%)). Median survival was 3.8 months, and 6 month overall survival rate was 32% (95% CI 19-47%). Mutational analysis and EGFR expression were performed on 29 patients, with 93% having KRAS mutations, none having EGFR mutations, and 86% expressing EGFR. Neither KRAS mutational status nor EGFR expression was associated with survival.

CONCLUSIONS

Erlotinib dose escalated to rash was well tolerated but not associated with significant efficacy in non-selected patients with advanced pancreatic cancer.

Characterization of published errors in high-impact oncology journals

PURPOSE

To assess the frequency and propagation rate of published errors in the oncology literature and to determine possible contributing factors.

METHODS

We reviewed 10 major oncology journals to determine variability in the online presentation of errata. Canadian oncologists were surveyed regarding characteristics that may influence error propagation. Errors published during 2004-2007 in the Journal of Clinical Oncology (jco) and the Journal of the National Cancer Institute (jnci) were classified as trivial or serious (that is, whether change in outcome was involved). The frequency of citation and error propagation was determined for serious errors.

RESULTS

Of the 10 journals reviewed, 9 present links from the original article to the erratum; in 4 of those 9 journals, at least 1 link was missing. Survey results indicate that 33% of oncologists do not read errata, and 45% have read only the abstract when referencing an article. Although 59% of oncologists have noticed errors in cancer publications, only 13% reported the error. Together, jco and jnci published 190 errata, for an error rate of 4% ± 1% (standard deviation) annually; 26 of 190 errors were serious (14%). The median time from publication of the article to the corresponding erratum was 3.5 months for trivial errors as compared with 8.3 months for serious errors (p = 0.03). Error propagation in citations before and after publication of the erratum was 15% and 2% respectively (p < 0.01).

CONCLUSIONS

Error rates in high-impact oncology journals average 4%, which is likely an underestimate, because errors noticed by readers are not consistently reported. Propagation of serious errors decreases, but still continues, after publication of errata.

Characterization of published errors in high-impact oncology journals

6627

Background: Knowledge within oncology is disseminated primarily via peer-reviewed journals. The potential for dissemination of erroneous data exists, an issue that has not been explored in oncology. We evaluated errata from the Journal of Clinical Oncology and the Journal of the National Cancer Institute published between 2004–2007. Methods: Two authors independently abstracted data regarding errata and classified them as trivial (eg typographical error) or serious (eg change in outcome). For serious errors, the frequency of citation and error propagation was determined using the Science Citation Index in Web of Science. For publications cited > 150 times, a random sample of 10% were evaluated for error propagation. Canadian oncologists were surveyed regarding attitudes towards published errata. Results: There were 190 published errors, out of a total of 5118 papers, for an error rate of 4 ± 1% (SD) per year. 26/190 errors were identified as serious (14%). The median time from publication of the original article to publication of the erratum was 3.5 mo for trivial errors compared to 8.3 mo for serious errors (p = 0.03). A median of 1 error per article was reported for papers with trivial errors compared to a median of 2 errors per article with serious errors (p < 0.01). The 26 articles with serious errors were cited 256 times before publication of the error and 1056 times afterwards; of these, 96 and 527, respectively, were evaluated for propagation. Error propagation occurred in 14.6% of the citations published before error publication, and in 3.4% of citations published afterwards (p < 0.001). Survey results indicate that 30% of oncologists do not read the erratum section of journals, and that 45% of oncologists have only read the abstract of an article before citing it in a publication. Although 58% of oncologists have noticed errors in cancer publications, only 15% of these errors were reported. Conclusions: Error rates in high impact oncology journals average 4% per year, but this is likely an underestimate since errors noticed by readers are not consistently reported to the journal. The accuracy of articles submitted for publication is of utmost importance; while error propagation decreases after erratum publication, serious errors continue to be propagated in the literature.

No significant financial relationships to disclose.

Trends in the application of dynamic allocation methods in multiarm cancer clinical trials

6550

Background: In multiarm oncology clinical trials there is always a risk that the treatment groups could be imbalanced for a prognostic factor, potentially biasing treatment comparisons and compromising the validity of the results. Stratified randomization (SR) is frequently used to reduce imbalances. Dynamic allocation (DA), also known as minimization, is a controversial and largely nonrandom method of treatment allocation that can incorporate more prognostic factors than traditional SR methods. Proponents argue that results from clinical trials implementing DA are potentially more credible, while opponents claim there is little added benefit, increased complexity, and the statistical properties are not fully understood. We reviewed multi-arm cancer trials published between 1995–2005 to describe trends in the application of DA methods. Methods: 476 clinical trials with at least 100 patients in each arm, published in 13 major journals were reviewed. Manuscripts were grouped by impact factor (IF) of the publishing journal into low (<10), medium (10–20) and high (20+) categories. Trial-specific factors associated with publication were collected along with details of allocation method. Results: 112 (24%) trials described using DA for assigning patients to treatment. 79% of trials employing DA methods included 3 or more stratification factors, compared with only 36% of other trials (p < 0.001). Reported use of DA was similar between industry and non-industry sponsored studies (p = 0.85) and by geographical region (p = 0.73). Of 364 trials which did not describe using DA, 103 (28%) reported using SR, but a statement describing stratification on at least one factor was included in 291 (80%) trials. A trend was observed that reported use of both DA (p = 0.072) and SR (p = 0.067) methods increased over time. DA was associated with publication in higher IF journals univariately (OR = 1.67, 95% CI 1.11–2.52, p=0.014) and after adjusting for identified prognostic factors (OR = 1.70, 95% CI 1.06–2.73, p = 0.028). No association between SR and higher IF journal publication was observed (p = 0.52 univariately and p = 0.44 adjusting for other factors). Conclusions: DA is frequently used in cancer clinical trials. Reported use of DA, but not SR, is associated with publication in high IF journals.

No significant financial relationships to disclose.

Correlation of changes between 2-year disease-free survival and 5-year overall survival in adjuvant breast cancer trials from 1966 to 2006

BACKGROUND

Although disease-free survival (DFS) is accepted as a valid end point in adjuvant breast cancer trials, improvement in 2-year DFS has never been formally established as an adequate correlate for 5-year overall survival (OS). We set out to ascertain if changes in 2-year DFS can be used to accurately predict 5-year OS changes.

DESIGN

We conducted a systematic Medline search (1966-2006) for randomized adjuvant breast cancer trials of >100 patients per arm with 2-year DFS and 5-year OS data. A univariate regression model weighted by trial sample size was constructed to determine whether 2-year DFS differences between treatment arms within trials were predictive of 5-year OS differences.

RESULTS

A total of 126 studies containing 149 treatment comparisons met the inclusion criteria. Difference in 2-year DFS was a significant predictor of difference in 5-year OS. For every 1% increase in 2-year DFS difference, the 5-year OS difference increased by 0.5%-0.55%. The proportion of variation explained ranged from 0.38 to 0.42, with a wide prediction interval.

CONCLUSION

There is a statistically significant correlation, of moderate strength, between difference in 2-year DFS between treatment comparisons and difference in 5-year OS but the correlation is not strong enough to be used as a predictor.

Correlation between changes in 2- or 3-year disease-free survival (DFS) and 5-year overall survival (OS) in adjuvant breast cancer trials from 1966–2006

581

Background: Although disease-free survival (DFS) is accepted as a valid endpoint in adjuvant breast cancer trials, improvement in 2- or 3-year DFS has never been formally established as an adequate surrogate for 5- or 10-year overall survival (OS). We set out to establish if changes in 2- or 3-year DFS can be used to accurately predict changes in 5- or 10-year OS. Method: We conducted a systematic Medline search for phase III randomized adjuvant breast cancer trials published between 1966–2006 with >100 patients per arm with data for 2- and 3-year DFS as well as 5- or 10-year OS. Only trials of systemic therapies (e.g. chemotherapy, hormonal therapy) were included. We excluded studies investigating the effects of surgery, radiotherapy and neoadjuvant treatment. A univariate regression model weighted by trial sample size was constructed to determine if changes in 2-year DFS between treatment arms within trials were predictive of changes in 5- year OS. Computations of the correlation coefficient, proportion of variation, predicted estimates and 95% prediction interval were undertaken. Results: 126 studies containing 149 treatment arms met the inclusion criteria. Median sample size per trial was 533 and median follow up time was 81 months. Only 26 trials provided 10-year OS data thus association with 10-year OS was not attempted. Results were similar between analyses using either 2- or 3-year DFS, hence only 2-year DFS statistics are reported. 2-year DFS was a significant predictor of 5-year OS regardless of what other covariates were included (p<0.001). For every 1% increase in difference between treatment arms in 2-year DFS, the estimated difference in 5-year OS increased by 0.52%. The proportion of variation explained (R2) ranged from 0.38 to 0.49, with a wide prediction interval. Indeed, if a future trial accrued 1,000 patients and the 2-year DFS in the experimental arm was better than the control by 10%, the 95% prediction interval would still range from -0.2% to 11%. Conclusion: There is a statistically significant correlation, of moderate strength, between changes in 2-year DFS between treatment arms and changes in 5-year OS but the wide prediction intervals mean that the correlation is not strong enough to be used as a surrogate.

No significant financial relationships to disclose.

Role of AVP in mediating the altered core temperature response to a simulated open field in pregnant rats

Near the term of pregnancy, rats have an attenuated core temperature response on exposure to a novel environment (e.g., a simulated open field) compared with that observed early in pregnancy or in nonpregnant rats. The present experiments were carried out on 26 nonpregnant and 26 pregnant rats to test the hypothesis that arginine vasopressin, functioning as an endogenous antipyretic substance in the central nervous system, mediates this attenuated core temperature response. Exposure to a simulated open field after intracerebroventricular (ICV) vehicle produced a significant increase in core temperature in both nonpregnant and pregnant animals, the magnitude and duration of which were greater in the nonpregnant rats. In nonpregnant rats, exposure to a simulated open field after ICV vasopressin V(1)-receptor antagonist altered the pattern of the core temperature response but not the core temperature index compared with that observed on exposure to a simulated open field after ICV vehicle. In pregnant animals, ICV vasopressin V(1)-receptor antagonist did not alter the core temperature response to a simulated open field compared with that observed after ICV vehicle. Thus our data do not support the hypothesis that a pregnancy-related activation of arginine vasopressin attenuates the core temperature response to a simulated open field in rats near the term of pregnancy.

Influence of nicotine on the core temperature response to a novel environment in pregnant rats

Exposure of a male or nonpregnant female rat to a novel environment, such as a simulated open field, induces a transient increase in core temperature, which is often called stress-induced hyperthermia. Pregnancy alters this response such that the core temperature index increases significantly during exposure to a simulated open field on day 10 but not on days 15 and 20 of gestation in rats. The present experiments were carried to investigate the effect of chronic administration of nicotine (0, 1, 2, 4, or 8 mg.kg-1.24 h-1 for 13-15 days) on the core temperature response to a simulated open field in chronically instrumented pregnant (day 20 or 21 of gestation) and nonpregnant Sprague-Dawley rats. In nonpregnant rats, the core temperature index increased more during exposure to a simulated open field after chronic administration of nicotine at all doses than after chronic administration of vehicle; the core temperature response was not dependent on the dose of nicotine. In pregnant rats, significant increases in core temperature as well as in the core temperature index occurred only during exposure to a simulated open field after chronic administration of nicotine in doses of 2, 4, or 8 mg.kg-1.24 h-1; the core temperature response was dependent on the dose of nicotine. Our data provide evidence that chronic exposure to nicotine enhances the core temperature response to a simulated open field in nonpregnant rats and unmasks a maternal thermogenic response that is not seen to the same stimulus near term of pregnancy. The possible physiological consequences for the fetus are presently unknown and require investigation.

Pregnancy alters body-core temperature response to a simulated open field in rats

Exposure of a rat to a novel environment (e.g., a simulated open field) induces a transient increase in body-core temperature, which is often called stress-induced hyperthermia. Although pregnancy is known to influence thermoregulatory control, its effect on stress-induced hyperthermia is unknown. Therefore, 24 Sprague-Dawley rats (8 nonpregnant and 16 pregnant) were studied to test the hypothesis that pregnancy would alter the development of stress-induced hyperthermia after exposure to a simulated open field. Body-core temperature index increased significantly after exposure to a simulated open field in nonpregnant and gestation day-10 rats but not in gestation day-15 and day-20 rats. Thus our data provide evidence that pregnancy influences the body-core temperature response of rats exposed to a simulated open field in a gestation-dependent fashion. The functional consequences as well as the mechanisms involved remain to be determined.