Machine Learning Incorporating Host Factors for Predicting Survival in Head and Neck Squamous Cell Carcinoma Patients

Prognostication for cancer patients is integral for patient counseling and treatment planning, yet providing accurate prediction can be challenging using existing patient-specific clinical indicators and host factors. In this work, we evaluated common machine learning models in predicting head and neck squamous cell carcinoma (HNSCC) patients' overall survival based on demographic, clinical features and host factors. We found random survival forest had best performance among the models evaluated, which achieved a C-index of 0.729 and AUROC of 0.792 in predicting two-year overall survival. In addition, we verified that host factors are independently predictive of HNSCC overall survival, which improved the C-index by a margin of 0.026 and the AUROC by 0.034. Due to the strong correlation among host factors, we showed that proper dimension reduction is an important step before their incorporation into the machine learning models, which provides a host factor score reflecting the patients' nutrition and inflammation status. The score by itself showed excellent discriminating capacity with the high-risk group having a hazard ratio of 3.76 (1.93-7.32, p < 0.0001) over the low-risk group. The hazard ratios were further improved to 7.41 (3.66-14.98, p < 0.0001) by the random survival forest model after including demographic and clinical features.

MKP-1 is required to limit myeloid-cell mediated oral squamous cell carcinoma progression and regional extension

Mitogen-activated protein kinases (MAPKs) require MAPK phosphatases (MKPs) for deactivation of MAPK intracellular signaling. MKP-1 (encoded by Dusp1) is a key negative regulator of MAPKs and prior reports have indicated that MKP-1 regulates oral cancer-associated inflammation and leukocyte infiltration.

OBJECTIVE

To determine the significance of myeloid-based expression of MKP-1 in oral cancer.

METHODS

The Cancer Genome Atlas (TCGA) was used to address DUSP1 expression in oral squamous cell carcinoma (OSCC). Syngeneic and carcinogen-induced mouse models using global and myeloid-specific Dusp-1 deficient mice with immunophenotypic, histologic, and transcriptomic analyses and in vitro migration assays.

RESULTS

Data from TCGA indicates the DUSP1 expression is inversely related to oral cancer burden and nodal involvement. Using murine models of OSCC, the role of MKP-1 signaling in tumor associated macrophages (TAMs) was assessed. Dusp1-deficient mice had increased tumor burden and TAM infiltrate with increased M2 macrophage polarization. Transcriptomic signatures of TAMs from Dusp1-deficent mice indicated a pro-metastatic phenotype as well as concomitant differences in myeloid-associated genes, cytokine/chemokine signaling, and Notch signaling consistent with tumor progression. In vitro and in vivo assays revealed mouse OSCC cells had a higher migration rate using TAM cell-free supernatant from Dusp1 deficiency mice compared to controls with enhanced regional cervical lymph node metastasis, respectively. To validate TAM studies using implantable mouse models, an OSCC progression model with conditional myeloid-specific Dusp-1 deficient mice demonstrated enhanced OSCC disease progression, characterized by advanced onset, histological stage, and tumor burden.

CONCLUSION

Myeloid-based Dusp1-deficiency increases OSCC burden and metastasis through alteration in TAM recruitment, gene profile, and polarity suggesting that MKP-1 could be a viable target to reprogram TAM to limit local/regional OSCC extension.

Financial Counseling Is Associated with Reduced Financial Difficulty Scores in Head and Neck Cancer Patients Treated with Radiation Therapy

BACKGROUND

Financial toxicity (FT) can be devastating to cancer patients, and solutions are urgently needed. We investigated the impact of financial counseling (FC) on FT in head and neck cancer (HNC) patients.

METHODS

Via a single-institution database, we reviewed the charts of HNC patients who underwent definitive or post-operative radiotherapy, from October 2013 to December 2020. Of these patients, 387 had provided baseline and post-treatment information regarding financial difficulty. In July 2018, a dedicated financial counselor was provided for radiation therapy patients and we subsequently examined the impact of FC on financial difficulty scores.

RESULTS

Following the hiring of a dedicated financial counselor, there was a significant increase in the proportion of patients receiving FC (5.3% vs. 62.7%, p < 0.0001). Compared with baseline scores, patients who did not undergo FC had a significant increase in reported financial difficulty at the end of treatment (p = 0.002). On the other hand, there was no difference in pre- and post-treatment scores in patients who had received FC (p = 0.588). After adjusting for gender and nodal status with a multiple linear regression model, FC was significantly associated with change in financial difficulty (β = -0.204 ± 0.096, p = 0.035). On average, patients who received FC had a 0.2 units lower change in financial difficulty score as compared with those with the same gender and nodal stage but without FC.

CONCLUSIONS

Providing a dedicated financial counselor significantly increased the proportion of HNC receiving FC, resulting in the stabilization of financial difficulty scores post-treatment. Based on a multiple linear regression model, FC was independently associated with reduced financial difficulty. The employment of a financial counselor may be a viable, hospital-based approach to begin to address FT in HNC.

Matched pair analysis for comparison of survival outcome of alternative regimens to standard three-weekly cisplatin-based concurrent chemoradiation of head and neck cancer

Background

To compare head and neck cancer (HNC) patients treated with three-weekly versus weekly cisplatin-based or other chemotherapy-based concurrent chemoradiation (CRT) and CRT with versus without induction chemotherapy (ICT) to investigate differences in overall survival (OS) and cancer-specific survival (CSS).

Methods

HNC patients treated with definitive or adjuvant CRT at Roswell Park Comprehensive Cancer Center between 2003 and 2017 were retrospectively reviewed. Propensity score matching was performed to obtain three sets of balanced matched pairs: three-weekly and weekly cisplatin CRT, three weekly and non-cisplatin CRT, CRT with and without ICT. Multivariate Cox regression and Kaplan-Meier analyses were used to estimate and compare survival outcomes.

Results

A total of 623 patients received either definitive (81%) or post-operative (19%) RT. Of these, 283 patients concurrently received three-weekly cisplatin (45%); 189 patients (30%) received weekly cisplatin; 151 patients (24%) received non-cisplatin regimen. Median follow-up was 55.4 months (interquartile range, 38.0–88.7). Patients who received CRT alone and those who received ICT and CRT had no difference in 5-year OS (51.5% and 41.0% respectively, P=0.53) and CSS (64.9% and 49.7% respectively, P=0.21). Compared to patients who received three-weekly cisplatin, patients who received weekly cisplatin had no difference in 5-year OS (59.3% vs. 54.1%, P=0.35) and CSS (70.3% vs. 62.4%, P=0.09); patients who received non-cisplatin CRT also had no difference in 5-year OS (54.5% vs. 58.3%, P=0.51) and CSS (67.5% vs. 64.7%, P=0.45).

Conclusions

No significant difference in OS and CSS was observed in any of the three pairs of CRT regimens. ICT prior to CRT did not improve survival of CRT alone. Non-cisplatin and weekly cisplatin regimens did not prove to be inferior to the standard three-weekly cisplatin.

Matched pair analysis to evaluate weight loss during radiation therapy for head and neck cancer as a prognostic factor for survival

Background

One frequent consequence of radiation therapy (RT) for head and neck cancer (HNC) is weight loss (WL). HNC patients reportedly lose about 9% of their weight during treatment, regardless of pre-treatment WL and nutritional support. We investigated whether high WL during RT has an association with overall (OS) and cancer-specific survival (CSS).

Methods

We retrospectively reviewed weight during RT in HNC patients treated at Roswell Park Comprehensive Cancer Center between 2003 and 2017. High WL was defined as greater than or equal to the median WL. Logistic regression analysis was performed to identify predictors for WL during RT. Multivariate Cox regression and Kaplan-Meier analyses were used to estimate survival outcomes. Propensity score matching was performed to obtain balanced matched-pairs and compare survival outcomes.

Results

A total of 843 patients received either definitive (71%) or post-operative (29%) RT. Median follow-up was 53.6 months [interquartile range (IQR) 35.7–88.9]. Median WL was 5.8% (IQR 0.24–10.6) from baseline weight. Patients with high WL had better OS [hazard ratio (HR) 0.75, 95% confidence interval (CI), 0.61–0.93, P=0.01] and CSS (HR 0.71, 95% CI, 0.55–0.93, P=0.01). 258 matched-pairs were analyzed. Median follow-up was 54.8 months (IQR 35.8–90.4). Median OS was 39.2 months (IQR 21.4–75.7) for high WL versus 36.7 months (IQR 14.6–61.7) for low WL cohorts (P=0.047).

Conclusions

Different from previous reports, this study shows that patients with less WL have worse OS. WL during RT may not be a reliable marker for worse prognosis. A better way to evaluate malnutrition in patients undergoing RT is warranted.

Association of significant financial burden with survival for head and neck cancer patients treated with radiation therapy

OBJECTIVE

To assess the association between financial toxicity and survival in patients with head and neck cancer (HNC).

MATERIALS AND METHODS

Using a single-institution database, we retrospectively reviewed HNC patients treated at Roswell Park Comprehensive Cancer Center treated with definitive or postoperative radiation therapy between 2013 and 2017. Kaplan-Meier method and log-rank tests were used to analyze survival outcomes. Propensity score matching on all clinically relevant baseline characteristics was performed to address selection bias. All statistical tests were two-sided and those less than 0.05 were considered statistically significant.

RESULTS

Of a total of 284 HNC patients (age: median 61 years, IQR 55-67; 220 [77.5%] men), 204 patients (71.8%) received definitive radiation and 80 patients (28.2%) received adjuvant radiation. There were 41 patients (14.4%) who reported high baseline financial toxicity. Chemotherapy was used in 237 patients (83.5%). On multivariable analysis, those with high financial toxicity exhibited worse overall survival (hazards ratio [HR] 1.75, 95% confidence interval [CI] 1.05-2.94, p = 0.03) and cancer specific survival (HR 2.28, 95% CI 1.31-3.96, p = 0.003). On matched pair analysis of 66 patients, high financial toxicity remained associated with worse OS (HR 2.72, 95% CI 1.04-7.09, p = 0.04) and CSS (HR 3.75, 95% CI 1.22-11.5, p = 0.02).

CONCLUSION

HNC patient reported baseline financial toxicity was significantly correlated with both decreased overall and cancer specific survival. These significant correlations held after match pairing. Further research is warranted to investigate the impact of financial toxicity in HNC and mitigate its risk.

Matched pair analysis to evaluate the impact of hospitalization during radiation therapy as an early marker of survival in head and neck cancer patients

BACKGROUND

Complications from radiotherapy (RT) alone or combined with surgery and/or chemotherapy for head and neck cancer (HNC) sometimes necessitate hospitalization. Our aim was to evaluate the frequency, cause, and survival outcomes associated with hospitalizations in patients undergoing RT for HNC.

PATIENTS AND METHODS

Using a retrospective single-institution database, we reviewed hospitalization records of HNC patients treated at Roswell Park Comprehensive Cancer Center with definitive or post-operative RT between 2003 and 2017. Patients who were admitted during treatment and within 90-days post-RT were identified. Multivariate analyses, Kaplan-Meier statistics, and analysis on propensity score matching were performed to obtain matched-pair, after matching baseline characteristics, such as age, gender, smoking, tumor staging, p16 status, and treatments received.

RESULTS

839 patients were eligible for analysis. Median follow-up was 34.8 months (Interquartile range [IQR] 15.6-64.8). 595 (71%) received definitive RT and 244 (29%) received adjuvant RT. Chemotherapy was used in 671 patients (80%). 171 patients (20%) had at least one hospitalization. Dehydration (40%) and fever (29%) were the most frequent causes of admission. Hospitalized patients had significantly worse overall survival (OS) (Hazards ratio [HR] 1.61, 95% CI 1.26-2.07, p < 0.001) and cancer-specific survival (CSS) (HR 1.45, 95% CI 1.07-1.95, p = 0.02). 163 matched pairs had median follow-up of 58.6 months (IQR 37.6-85.0). Median OS was 34.5 months (IQR 13.3-58.0) for hospitalized versus 44.2 months (IQR 20.3-78.7) for non-hospitalized patients (p = 0.01).

CONCLUSION

This study reveals significantly worse OS and CSS for patients hospitalized during RT for HNC. Hospitalization may be an early marker for worse survival.

Monocyte cell membrane-derived nanoghosts for targeted cancer therapy

Core-shell type 'nanoghosts' were synthesized with a drug-loaded biodegradable PLGA core and a monocyte cell membrane-derived shell. The nanoghosts were monodisperse with an average size <200 nm, and showed good serum stability for 120 h. Doxorubicin-loaded nanoghosts showed greater cellular uptake and cytotoxicity compared to non-coated nanoparticle controls in metastatic MCF-7 breast cancer cell lines.

Immediate versus deferred initiation of androgen deprivation therapy in prostate cancer patients with PSA-only relapse. An observational follow-up study

BACKGROUND

The optimal timing to start androgen deprivation therapy (ADT) in prostate cancer patients with rising prostate-specific antigen (PSA) as the only sign of relapse is unknown.

METHODS

We identified men with prostate cancer in the Cancer of the Prostate Strategic Urologic Research Endeavour (CaPSURE) study who would have been eligible (⩽ cT3aN0M0, primary radical prostatectomy or radiotherapy, PSA relapse as the only evidence of recurrence) for a randomised trial comparing 'immediate' versus 'deferred' ADT initiation. We emulated such trial by assigning patients to the 'immediate' strategy if they initiated ADT within 3 months of PSA relapse and to the 'deferred' strategy if they initiated ADT when they presented with metastasis, symptoms or a short PSA doubling time. We censored patients when they deviated from the assigned strategy and adjusted for this censoring via inverse probability weighting.

RESULTS

Of 2096 eligible patients (median age 69, interquartile range 63-75 years), 88% were white, 35% had a Gleason score ⩾ 7, 69% were treated with radical prostatectomy and 31% received radiotherapy only as primary treatment. The mean time from primary treatment to PSA relapse was 37.4 (standard deviation [SD] 34.2) months. Mean follow-up from primary treatment was 91.4 (SD 48.4) months. The adjusted mortality hazard ratio for immediate versus deferred ADT was 0.91 (95% confidence interval (CI), 0.52-1.60), which would be translated into a similar 5-year survival (difference between groups: -2.0% (95% CI: -10.0 to 5.9%).

CONCLUSION

Our analysis suggests that prostate cancer patients undergoing immediate ADT initiation within three months after PSA-only relapse had similar survival to those who deferred ADT initiation within 3 months after clinical progression.

Ewing sarcoma of the thyroid: report of 2 cases and review of the literature

BACKGROUND

Neuroendocrine tumors of the thyroid encompass a wide differential diagnosis. The most common is medullary thyroid carcinoma. One must consider other possibilities when a neuroendocrine thyroid tumor is calcitonin negative. We report 2 cases of Ewing sarcoma of the thyroid and discuss the differential diagnosis and workup of a calcitonin-negative neuroendocrine tumor of the thyroid.

METHODS/RESULTS

This is a retrospective review of 2 patients diagnosed with Ewing sarcoma of the thyroid and a review of the literature.

CONCLUSIONS

Ewing sarcoma of the thyroid is an exceedingly rare diagnosis, but should be included in the differential diagnosis for a thyroidal neuroendocrine lesion (especially in the absence of calcitonin). The use and interpretation of immunohistochemistry (IHC) and fluorescent in situ hybridization are essential in making the correct diagnosis.

Active surveillance: does serial prostate biopsy increase histological inflammation?

BACKGROUND

Active surveillance (AS) is an appropriate management strategy for men with low-risk prostate cancer. Most protocols recommend repeated prostate biopsy every 12-24 months. The purpose of this paper is to describe histological inflammation patterns in men on AS who underwent serial prostate biopsy for disease monitoring.

METHODS

We reviewed records of men on AS from January 1999 through February 2011 who had a diagnostic plus ≥1 repeat transrectal ultrasound-guided biopsies performed at our institution. The type and degree of inflammatory infiltrate were grossly reviewed and scored for each patient's biopsy by a single pathologist. Relationship of inflammation severity and number of serial biopsies was assessed using a repeated measures mixed model. Unpaired t-test and χ(2)-square analysis assessed variance in degree of inflammation and location of inflammation relative to cancer grade progression defined as Gleason sum increase.

RESULTS

Fifty-six men met study inclusion criteria. Mean age was 62.1 (6.5) years, 71% were stage cT1c, 79% had a PSA level <10 ng ml(-1), and 98% had diagnostic Gleason sum ≤6. A small, statistically significant increase in maximum chronic inflammation (CI) scores with greater number of repeat biopsies was observed. CI scores were not associated with number of biopsies based on upgrade status. The main limitation to our study is our small sample size. Potential unmeasured confounders, such as unreported antibiotic use or symptomatic prostatitis, may have also affected our findings.

CONCLUSIONS

In this pilot study of 56 men on AS for localized prostate cancer, degree of chronic histological inflammation increased with greater number of prostate biopsies, but was not associated with subsequent risk of grade progression.

PSA screening: determinants of primary-care physician practice patterns

BACKGROUND

The effect of practice guidelines and the European Randomised Screening for Prostate Cancer (ERSPC) and Prostate, Lung, Colorectal and Ovarian (PLCO) trials on PSA screening practices of primary-care physicians (PCPs) is unknown.

METHODS

We conducted a national cross-sectional on-line survey of a random sample of 3010 PCPs from July to August 2010. Participants were queried about their knowledge of prostate cancer, PSA screening guidelines, the ERSPC and PLCO trials, and about their PSA screening practices. Factors associated with PSA screening were identified using multivariable linear regression.

RESULTS

A total of 152 (5%) participants opened and 89 completed the on-line survey, yielding a response rate of 58% for those that viewed the invitation. Eighty percent of respondents correctly identified prostate cancer risk factors. In all, 51% and 64% reported that they discuss and order PSA screening for men aged 50-75 years, respectively. Fifty-four percent were most influenced by the US Preventative Services Task Force (USPSTF) guidelines. Also, 21% and 28% of respondents stated that their PSA screening practices were influenced by the ERSPC and PLCO trials, respectively. Medical specialty was the only variable associated with propensity to screen, with family medicine physicians more likely to use PSA screening than internists (β=0.21, P=0.02).

CONCLUSIONS

Half of the physicians surveyed did not routinely discuss PSA screening with eligible patients. The impact of the ERSPC and PLCO trials on PSA screening practices was low among US PCPs. USPSTF recommendations for PSA screening continue to be the strongest influence on PCPs' propensity to use PSA screening.

Demographic factors associated with the diet quality of older US men: baseline data from the Osteoporotic Fractures in Men (MrOS) study

OBJECTIVE

Throughout the world, the proportion of the male population aged 65 years and older is increasing. Yet, we have limited information regarding diet quality and predictors of diet quality in this segment of the population. The objectives of the current analyses are to describe the diet quality of a cohort of men >65 years of age, and identify lifestyle factors associated with poor diet quality.

METHODS

We present a cross-sectional analysis of the diet quality of 5928 men, aged 65-100 years, who are participants in the Osteoporotic Fractures in Men (MrOS) cohort study. Dietary intake was determined using a modified Block 98 food-frequency questionnaire. Diet quality was calculated using the previously validated Diet Quality Index-Revised (DQI-R). Univariate and multivariate modelling was used to estimate the variance in diet quality predicted by a number of sociodemographic factors, including age, race/ethnicity, body mass index (BMI), marital status, education, smoking status, physical activity, self-perceived health and nutritional supplement use.

RESULTS

Overall, we found that in this geographically diverse group of older men, diet quality was low, with a mean modified DQI-R for the entire study population of 62.5 (standard deviation 13.1) out of an ideal of 100. Further, younger age, very low total calorie intake (< or = 1187 kcal day- 1), higher BMI, residence in a North or Southeast community, being of African-American or Hispanic race, being less educated, not using dietary supplements and smoking were each significant independent predictors of a poorer diet.

CONCLUSION

These data may prove useful in both understanding the dietary intake of older US men as it relates to published dietary guidelines, and for targeting future dietary intervention programmes.

Highly elevated PSA and dietary PhIP intake in a prospective clinic-based study among African Americans

African-American men die from prostate cancer (PC) nearly twice as often as white US men and consume about twice as much of the predominant US dietary heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a genotoxic rat-prostate carcinogen found primarily in well-cooked chicken and beef. To investigate the hypothesis that PhIP exposure increases PC risk, an ongoing prospective clinic-based study compared PC screening outcomes with survey-based estimates of dietary PhIP intake among 40-70-year-old African-American men with no prior PC in Oakland, CA. They completed food-frequency and meat-cooking/consumption questionnaires and had a prostate-specific antigen (PSA) test and digital-rectal exam. Results for 392 men indicated a 17 (+/-17) ng/kg day mean (+/-1 s.d.) daily intake of PhIP, about twice that of white US men of similar age. PhIP intake was attributable mostly to chicken (61%) and positively associated (R(2)=0.32, P<0.0001) with saturated fat intake. An odds ratio (95% confidence interval) of 31 (3.1-690) for highly elevated PSA > or =20 ng/ml was observed in the highest 15% vs lowest 50% of estimated daily PhIP intake (> or =30 vs < or =10 ng/kg day) among men 50+ years old (P=0.0002 for trend) and remained significant after adjustment for self-reported family history of (brother or father) PC, saturated fat intake and total energy intake. PSA measures were higher in African-American men with positive family history (P=0.007 all men, P<0.0001 highest PSA quartile). These preliminary results are consistent with a positive association between PhIP intake and highly elevated PSA, supporting the hypothesis that dietary intervention may help reduce PC risk.

History of diabetes, clinical features of prostate cancer, and prostate cancer recurrence-data from CaPSURE (United States)

OBJECTIVES

There is a growing epidemiologic literature suggesting an inverse association between history of diabetes and risk of incident prostate cancer. To our knowledge, the relationship between diabetes and tumor features and risk of recurrence among men with prostate cancer has not been examined previously. We hypothesized that men with diabetes would present with more favorable prostate cancer and experience lower risk of recurrence.

METHODS

We identified 691 men with diabetes at the time of prostate cancer diagnosis, among 6722 men diagnosed with prostate cancer in 1989 to 2002 within CaPSURE(TM), a community-based prostate cancer registry study. We compared clinical and socio-demographic variables by diabetes status, using chi2 tests, t-tests, and multinomial logistic regression. We examined recurrence rates for prostate cancer among patients with and without diabetes using Kaplan-Meier log-rank tests and Cox proportional hazard models.

RESULTS

In multivariate analyses, history of diabetes was not associated with any diagnostic clinical parameter, and treatment-specific recurrence rates for prostate cancer generally did not differ by diabetes history. Among men with low-prognostic risk or who were younger at prostate cancer diagnosis, being diabetic (versus not) was associated with an elevated risk of recurrence after radiation therapy, in multivariate analyses.

CONCLUSIONS

Contrary to data suggesting that diabetes may be modestly protective against risk of incident prostate cancer, we did not observe any evidence of an inverse association between history of diabetes and aggressiveness at diagnosis or risk of recurrence, in this population of men with prostate cancer.

Total and specific complementary and alternative medicine use in a large cohort of men with prostate cancer

OBJECTIVES

To assess specific complementary and alternative medicine (CAM) use in the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE), a large, community-based national registry of men with prostate cancer.

METHODS

We examined more than 50 types of CAM use in a large, national, community-based registry of men with prostate cancer (CaPSURE). Participants completed biannual surveys within 2 years of diagnosis and treatment. We analyzed associations of CAM use with sociodemographic and clinical features, using chi-square tests and multivariate logistic regression.

RESULTS

One third of 2582 respondents reported using CAM. Common practices included vitamin and mineral supplements (26%), herbs (16%), antioxidants (13%), and CAM for prostate health (12%; eg, saw palmetto, selenium, vitamin E, lycopene). In multivariate analyses, users were more likely to have other comorbid conditions, worse cancer grade at diagnosis, higher incomes, more education, and to live in the West.

CONCLUSIONS

Complementary and alternative medicine use was associated with sociodemographic and clinical characteristics in this large sample of men with prostate cancer. These results should be considered by health care professionals counseling men with prostate cancer regarding diet and secondary prevention.

Dairy products, calcium, and prostate cancer risk in the Physicians' Health Study

BACKGROUND

A high calcium intake, mainly from dairy products, may increase prostate cancer risk by lowering concentrations of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], a hormone thought to protect against prostate cancer. The results of epidemiologic studies of this hypothesis are inconclusive.

OBJECTIVE

We investigated the association between dairy product and calcium intakes and prostate cancer risk in the Physicians' Health Study, a cohort of male US physicians.

DESIGN

At baseline, the men answered abbreviated dietary questionnaires. During 11 y of follow-up, we documented 1012 incident cases of prostate cancer among 20885 men. We estimated dairy calcium intake on the basis of consumption of 5 major dairy products and used logistic regression to estimate relative risk.

RESULTS

At baseline, men who consumed >600 mg Ca/d from skim milk had lower plasma 1,25(OH)(2)D(3) concentrations than did those consuming < or =150 mg Ca/d [71 compared with 85 pmol/L (30.06 compared with 35.64 pg/mL); P = 0.005]. Compared with men consuming < or =0.5 daily servings of dairy products, those consuming >2.5 servings had a multivariate relative risk of prostate cancer of 1.34 (95% CI: 1.04, 1.71) after adjustment for baseline age, body mass index, smoking, exercise, and randomized treatment assignment in the original placebo-controlled trial. Compared with men consuming < or =150 mg Ca/d from dairy products, men consuming >600 mg/d had a 32% higher risk of prostate cancer (95% CI: 1.08, 1.63).

CONCLUSIONS

These results support the hypothesis that dairy products and calcium are associated with a greater risk of prostate cancer.

Milk intake, circulating levels of insulin-like growth factor-I, and risk of colorectal cancer in men

BACKGROUND

Milk and dietary calcium may have antiproliferative effects against colorectal cancer, but milk intake also raises serum levels of insulin-like growth factor-I (IGF-I). A high ratio of IGF-I to IGF-binding protein-3 (IGFBP-3) has been linked to an increased risk of colorectal cancer.

METHODS

In a case-control study nested in the Physicians' Health Study, plasma samples were collected from the period 1982 through 1983 from 14 916 men, aged 40-84 years, who also answered dietary questionnaires. Circulating levels of IGF-I and IGFBP-3 were assayed among 193 men who developed colorectal cancer during 13 years of follow-up and 318 age- and smoking-matched cancer-free control men. Conditional logistic regression was used to assess relative risks (RRs) of colorectal cancer for tertiles of IGF-I/IGFBP-3 and dietary factors. Statistical tests were two-sided.

RESULTS

Overall, there was a moderate but statistically nonsignificant inverse association between intake of low-fat milk or calcium from dairy food and colorectal cancer risk. Intake of dairy food (especially low-fat milk) was also positively and moderately associated with plasma levels of IGF-I, IGFBP-3, and IGF-I/IGFBP-3 among control men. We observed a statistically significant interaction between low-fat milk intake and IGF-I/IGFBP-3 in association with risk of colorectal cancer (P(interaction) =.03). Nondrinkers with IGF-I/IGFBP-3 in the highest tertile had a threefold higher risk than nondrinkers with IGF-I/IGFBP-3 in the lowest tertile (RR = 3.05; 95% confidence interval [CI] = 1.29 to 7.24), but no such increase was seen among frequent low-fat milk drinkers (RR = 1.05; 95% CI = 0.41 to 2.69). Conversely, among men with high IGF-I/IGFBP-3, frequent low-fat milk drinkers had a 60% lower risk (95% CI = 0.17 to 0.87; P(trend) =.02) than nondrinkers.

CONCLUSION

Intake of dairy products was associated with a modest increase in circulating IGF-I levels, but intake of low-fat milk was associated with lower risk of colorectal cancer, particularly among individuals with high IGF-I/IGFBP-3. This subpopulation, which is at increased risk of colorectal cancer, might benefit the most from specific dietary intervention.

Diet and prostate cancer risk in a cohort of smokers, with a specific focus on calcium and phosphorus (Finland)

BACKGROUND

Calcium, phosphorus, fructose, and animal protein are hypothesized to be associated with prostate cancer risk, potentially via their influence on 1,25-dihydroxyvitamin D3. We examined these nutrients and overall diet and prostate cancer risk in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study (ATBC Study).

MATERIALS AND METHODS

The ATBC Study was a randomized 2 x 2 trial of alpha-tocopherol and beta-carotene on lung cancer incidence conducted among Finnish male smokers; 27,062 of the men completed a food-use questionnaire at baseline, and comprise the current study population. There were 184 incident clinical (stage 2-4) prostate cancer cases diagnosed between 1985 and 1993. We used Cox proportional hazards models to examine associations between dietary intakes and prostate cancer.

RESULTS

We did not observe significant independent associations for calcium and phosphorus and prostate cancer risk. However, men with lower calcium and higher phosphorus intake had a multivariate relative risk of 0.6 (95% CI 0.3-1.0) compared to men with lower intakes of both nutrients, adjusting for age, smoking, body mass index, total energy, education, and supplementation group. Of the other foods and nutrients examined, none was significantly associated with risk.

DISCUSSION

This study provides, at best, only weak evidence for the hypothesis that calcium and phosphorus are independently associated with prostate cancer risk, but suggests that there may be an interaction between these nutrients.

The role of the MoFe protein alpha-125Phe and beta-125Phe residues in Azotobacter vinelandii MoFe protein-Fe protein interaction

Site-directed mutagenesis and gene-replacement techniques were used to substitute alanine for the MoFe protein alpha- and beta-subunit phenylalanine-125 residues both separately and in combination. These residues are located on the surface of the MoFe protein near the pseudosymmetric axis of symmetry between the alpha- and beta-subunits. Altered MoFe proteins that contain an alanine substitution at only one of the respective positions exhibit proton reduction activities of about 25-50% when compared to that of the wild-type protein. The lower level of proton reduction also corresponds with decreases in the rates of MgATP hydrolysis. The MoFe protein which contains alanine substitutions in both the alpha- and beta- subunits did not exhibit any proton reduction activity or MgATP hydrolysis. Stopped flow spectrophotometry of the singly substituted MoFe proteins indicate primary electron transfer rate constants approximately an order of magnitude slower than what is observed for wild-type MoFe protein, while no primary electron transfer is observed for the doubly substituted MoFe protein. The doubly substituted MoFe protein is able to interact with the Fe protein as shown by chemical crosslinking experiments. However, this protein does not form a tight complex with the Fe protein when treated with MgADP-AlF4- or when using the altered 127delta Fe protein. Stopped flow spectrophotometry was also used to quantitate the first-order dissociation rate constants for the two component proteins. These results suggest that the 125Phe residues are involved in an early event(s) that occurs upon component protein docking and could be involved in eliciting MgATP hydrolysis.

Construction and characterization of a heterodimeric iron protein: defining roles for adenosine triphosphate in nitrogenase catalysis

One molecule of MgATP binds to each subunit of the homodimeric Fe protein component of nitrogenase. Both MgATP molecules are hydrolyzed to MgADP and P(i) in reactions coupled to the transfer of one electron into the MoFe protein component. As an approach to assess the contributions of individual ATP binding sites, a heterodimeric Fe protein was produced that has an Asn substituted for residue 39 in the ATP binding domain in one subunit, while the normal Asp(39) residue within the other subunit remains unchanged. Separation of the heterodimeric Fe protein from a mixed population with homodimeric Fe proteins contained in crude extracts was accomplished by construction of a seven His tag on one subunit and a differential immobilized-metal-affinity chromatography technique. Three forms of the Fe protein (wild-type homodimeric Fe protein [Asp(39)/Asp(39)], altered homodimeric Fe protein [Asn(39)/Asn(39)], and heterodimeric Fe protein [Asp(39)/Asn(39)]) were compared on the basis of the biochemical and biophysical changes elicited by nucleotide binding. Among those features examined were the MgATP- and MgADP-induced protein conformational changes that are manifested by the susceptibility of the [4Fe-4S] cluster to chelation and by alterations in the electron paramagnetic resonance, circular dichroism, and midpoint potential of the [4Fe-4S] cluster. The results indicate that changes in the [4Fe-4S] cluster caused by nucleotide binding are the result of additive conformational changes contributed by the individual subunits. The [Asp(39)/Asn(39)] Fe protein did not support substrate reduction activity but did hydrolyze MgATP and showed MgATP-dependent primary electron transfer to the MoFe protein. These results support a model where each MgATP site contributes to the rate acceleration of primary electron transfer, but both MgATP sites must be functioning properly for substrate reduction. Like the altered homodimeric [Asn(39)/Asn(39)] Fe protein, the heterodimeric [Asp(39)/Asn(39)] Fe protein was found to form a high affinity complex with the MoFe protein, revealing that alteration on one subunit is sufficient to create a tight complex.

Supplemental vitamin E intake and prostate cancer risk in a large cohort of men in the United States

A clinical trial of vitamin E and beta-carotene supplementation for lung cancer prevention among male smokers in Finland recently reported an unexpected, strong protective effect of vitamin E against prostate cancer incidence and mortality. Our objective was to prospectively examine supplemental vitamin E intake and prostate cancer risk in a distinct U.S. population. In 1986, we identified 47,780 U.S. male health professionals, free from diagnosed cancer, who completed a dietary and lifestyle questionnaire; supplemental vitamin E and prostate cancer incidence were updated biennially through 1996. We estimated relative risks (RRs) from multivariate pooled logistic regression models. There were 1896 total (non-stage A1), 522 extraprostatic, and 232 metastatic or fatal incident prostate cancer cases diagnosed between 1986-1996. Men consuming at least 100 IU of supplemental vitamin E daily had multivariate RRs of 1.07 (95% confidence interval [CI], 0.95-1.20) for total and 1.14 (95% CI, 0.82-1.59) for metastatic or fatal prostate cancer compared with those consuming none. Current use, dosage, and total duration of use of specific vitamin E supplements or multivitamins were not associated with risk. However, among current smokers and recent quitters, those who consumed at least 100 IU of supplemental vitamin E per day had a RR of 0.44 (95% CI, 0.18-1.07) for metastatic or fatal prostate cancer compared with nonusers. Thus, supplemental vitamin E was not associated with prostate cancer risk generally, but a suggestive inverse association between supplemental vitamin E and risk of metastatic or fatal prostate cancer among current smokers and recent quitters was consistent with the Finnish trial among smokers and warrants further investigation.

Evidence that MgATP accelerates primary electron transfer in a Clostridium pasteurianum Fe protein-Azotobacter vinelandii MoFe protein nitrogenase tight complex

The nitrogenase catalytic cycle involves binding of the iron (Fe) protein to the molybdenum-iron (MoFe) protein, transfer of a single electron from the Fe protein to the MoFe protein concomitant with the hydrolysis of at least two MgATP molecules, followed by dissociation of the two proteins. Earlier studies found that combining the Fe protein isolated from the bacterium Clostridium pasteurianum with the MoFe protein isolated from the bacterium Azotobacter vinelandii resulted in an inactive, nondissociating Fe protein-MoFe protein complex. In the present work, it is demonstrated that primary electron transfer occurs within this nitrogenase tight complex in the absence of MgATP (apparent first-order rate constant k = 0.007 s-1) and that MgATP accelerates this electron transfer reaction by more than 10,000-fold to rates comparable to those observed within homologous nitrogenase complexes (k = 100 s-1). Electron transfer reactions were confirmed by EPR spectroscopy. Finally, the midpoint potentials (Em) for the Fe protein [4Fe-4S]2+/+ cluster and the MoFe protein P2+/N cluster were determined for both the uncomplexed and complexed proteins and with or without MgADP. Calculations from electron transfer theory indicate that the measured changes in Em are not likely to be sufficient to account for the observed nucleotide-dependent rate accelerations for electron transfer.

Spectroscopic evidence for changes in the redox state of the nitrogenase P-cluster during turnover

Biological nitrogen fixation catalyzed by nitrogenase requires the participation of two component proteins called the Fe protein and the MoFe protein. Each alphabeta catalytic unit of the MoFe protein contains an [8Fe-7S] cluster and a [7Fe-9S-Mo-homocitrate] cluster, respectively designated the P-cluster and FeMo-cofactor. FeMo-cofactor is known to provide the site of substrate reduction whereas the P-cluster has been suggested to function in nitrogenase catalysis by providing an intermediate electron-transfer site. In the present work, evidence is presented for redox changes of the P-cluster during the nitrogenase catalytic cycle from examination of an altered MoFe protein that has the beta-subunit serine-188 residue substituted by cysteine. This residue was targeted for substitution because it provides a reversible redox-dependent ligand to one of the P-cluster Fe atoms. The altered beta-188(Cys) MoFe protein was found to reduce protons, acetylene, and nitrogen at rates approximately 30% of that supported by the wild-type MoFe protein. In the dithionite-reduced state, the beta-188(Cys) MoFe protein exhibited unusual electron paramagnetic resonance (EPR) signals arising from a mixed spin state system (S = 5/2, 1/2) that integrated to 0.6 spin/alphabeta-unit. These EPR signals were assigned to the P-cluster because they were also present in an apo-form of the beta-188(Cys) MoFe protein that does not contain FeMo-cofactor. Mediated voltammetry was used to show that the intensity of the EPR signals was maximal near -475 mV at pH 8.0 and that the P-cluster could be reversibly oxidized or reduced with concomitant loss in intensity of the EPR signals. A midpoint potential (Em) of -390 mV was approximated for the oxidized/resting state couple at pH 8.0, which was observed to be pH dependent. Finally, the EPR signals exhibited by the beta-188(Cys) MoFe protein greatly diminished in intensity under nitrogenase turnover conditions and reappeared to the original intensity when the MoFe protein returned to the resting state.

Prospective study of colorectal cancer risk in men and plasma levels of insulin-like growth factor (IGF)-I and IGF-binding protein-3

BACKGROUND

Insulin-like growth factor-I (IGF-I) is a potent mitogen for normal and neoplastic cells, whereas IGF-binding protein-3 (IGFBP-3) inhibits cell growth in many experimental systems. Acromegalics, who have abnormally high levels of growth hormone and IGF-I, have higher rates of colorectal cancer. We therefore examined associations of plasma levels of IGF-I and IGFBP-3 with the risk of colorectal cancer in a prospective case-control study nested in the Physicians' Health Study.

METHODS

Plasma samples were collected at baseline from 14916 men without diagnosed cancer. IGF-I, IGF-II, and IGFBP-3 were assayed among 193 men later diagnosed with colorectal cancer during 14 years of follow-up and among 318 age- and smoking-matched control subjects. All P values are two-sided.

RESULTS

IGFBP-3 levels correlated with IGF-I levels (r=.64) and with IGF-II levels (r=.90). After controlling for IGFBP-3, age, smoking, body mass index (weight in kg/[height in m]2), and alcohol intake, men in the highest quintile for IGF-I had an increased risk of colorectal cancer compared with men in the lowest quintile (relative risk [RR]=2.51; 95% confidence interval [CI]=1.15-5.46; P for trend = .02). After controlling for IGF-I and other covariates, men with higher IGFBP-3 had a lower risk (RR=0.28; 95% CI=0.12-0.66; P for trend = .005, comparing extreme quintiles). The associations were consistent during the first and the second 7-year follow-up intervals and among younger and older men. IGF-II was not associated with risk.

CONCLUSIONS

Our findings suggest that circulating IGF-I and IGFBP-3 are related to future risk of colorectal cancer.

Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer (Sweden)

OBJECTIVES

Dairy products consistently have been associated with an increased risk of prostate cancer, yet the mechanism of this relationship remains unknown. Recent hypotheses propose that 1,25 dihydroxyvitamin D (1,25 D) is protective for prostate cancer. One study in the United States found that calcium consumption, which can lower circulating 1,25 D, was associated with higher risk of advanced prostate cancer, and we sought to address this hypothesis in a distinct population.

METHODS

We analyzed data from a population-based case-control study of prostate cancer conducted in Orebro, Sweden, with 526 cases and 536 controls. Using unconditional logistic regression models, we examined the relationship of dairy products, dietary calcium, phosphorous, and vitamin D with risk of total, extraprostatic, and metastatic prostate cancer.

RESULTS

Calcium intake was an independent predictor of prostate cancer (relative risk (RR) = 1.91, 95 percent confidence interval (CI) 1.23-2.97 for intake > or = 1183 vs. < 825 mg/day), especially for metastatic tumors (RR = 2.64, 95 percent CI 1.24-5.61), controlling for age, family history of prostate cancer, smoking, and total energy and phosphorous intakes. High consumption of dairy products was associated with a 50 percent increased risk of prostate cancer.

CONCLUSIONS

Our results support the hypothesis that high calcium intake may increase risk of prostate cancer, and this relation may underlie previously observed associations between dairy products and prostate cancer.

What causes prostate cancer? A brief summary of the epidemiology

In recent decades, prostate cancer has emerged as one of the most common diseases among older men, particularly in Western society. Several years ago, only age, race, and family history were known risk factors for this disease. However, today, much progress has been made towards discovering nutritional and hormonal risk factors for prostate cancer. Biomarkers, including testosterone and insulin-like growth factor, and nutritional factors, especially meat, fat, and dairy intake, have been linked to greater risk of disease. Higher consumption of selenium and vitamin E, fructose/fruits, and tomatoes all have been associated with reduced occurrence of prostate cancer, but as yet their efficacy for prevention remains unproven. The challenge of understanding the enigmas of this disease will continue into future decades, as we convert current knowledge into preventive and therapeutic recommendations.

Plasma insulin-like growth factor-I and prostate cancer risk: a prospective study

Insulin-like growth factor-I (IGF-I) is a mitogen for prostate epithelial cells. To investigate associations between plasma IGF levels and prostate cancer risk, a nested case-control study within the Physicians' Health Study was conducted on prospectively collected plasma from 152 cases and 152 controls. A strong positive association was observed between IGF-I levels and prostate cancer risk. Men in the highest quartile of IGF-I levels had a relative risk of 4.3 (95 percent confidence interval 1.8 to 10.6) compared with men in the lowest quartile. This association was independent of baseline prostate-specific antigen levels. Identification of plasma IGF-I as a predictor of prostate cancer risk may have implications for risk reduction and treatment.

Obesity, fat distribution, and weight gain as risk factors for clinical diabetes in men

OBJECTIVE

To investigate the relation between obesity, fat distribution, and weight gain through adulthood and the risk of non-insulin-dependent diabetes mellitus (NIDDM).

RESEARCH DESIGN AND METHODS

We analyzed data from a cohort of 51,529 U.S. male health professionals, 40-75 years of age in 1986, who completed biennial questionnaires sent out in 1986, 1988, 1990, and 1992. During 5 years of follow-up (1987-1992), 272 cases of NIDDM were diagnosed among men without a history of diabetes, heart disease, and cancer in 1986 and who provided complete health information. Relative risks (RRs) associated with different anthropometric measures were calculated controlling for age, and multivariate RRs were calculated controlling for smoking, family history of diabetes, and age.

RESULTS

We found a strong positive association between overall obesity as measured by body mass index (BMI) and risk of diabetes. Men with a BMI of > or = 35 kg/m2 had a multivariate RR of 42.1 (95% confidence interval [CI] 22.0-80.6) compared with men with a BMI < 23.0 kg/m2. BMI at age 21 and absolute weight gain throughout adulthood were also significant independent risk factors for diabetes. Fat distribution, measured by waist-to-hip ratio (WHR), was a good predictor of diabetes only among the top 5%, while waist circumference was positively associated with the risk of diabetes among the top 20% of the cohort.

CONCLUSIONS

These data suggest that waist circumference may be a better indicator than WHR of the relationship between abdominal adiposity and risk of diabetes. Although early obesity, absolute weight gain throughout adulthood, and waist circumference were good predictors of diabetes, attained BMI was the dominant risk factor for NIDDM; even men of average relative weight had significantly elevated RRs.

Self-understanding and reaching out to sick children and their families: an ongoing professional challenge

Health care professionals face a series of taxing, emotionally wrenching, painful experiences as they begin to care for frightened, ill children and their families. Loss, grief, overidentification with patients, and overwhelming anxiety are among their "occupational hazards." Open, frank discussion of intense feelings and reactions and mutual support are essential elements in helping caregivers to cope in ways that do not result in withdrawal from children and families. By developing strategies that reach out to patients and their families, professionals enhance their own personal professional gratification and self-esteem. The insights of parents are used extensively both to illustrate concepts and to emphasize the critical role parents can play as "resources" for professionals and "partners in care."

Play and the abused child: implications for acute pediatric care

Child maltreatment is a major pediatric health care concern. A large number of children will be admitted to inpatient pediatric settings for treatment of injuries that have resulted from child abuse and/or neglect. This article focuses on the role of play during the abused child's acute inpatient admission. Sensitive crisis management and careful assessment and treatment of the child through play are significant contributions to the comprehensive care of such children.

Parenting the chronically ill child in the hospital: issues and concerns

Chronic childhood illness and hospitalization are stressful events within the family unit. Parental response to the crisis of hospitalization profoundly affects the child's recovery process. This article discusses a team approach toward assessing and understanding parental reactions, methods of offering assistance and guidance, and basic issues and problems concerning staff-parent relationships. The focus is on the pediatric health care "team" as an agent for aiding families.