Stable isotopes of tree rings reveal seasonal-to-decadal patterns during the emergence of a megadrought in the Southwestern US.

Recent evidence has revealed the emergence of a megadrought in southwestern North America since 2000. Megadroughts extend for at least 2 decades, making it challenging to identify such events until they are well established. Here, we examined tree-ring growth and stable isotope ratios in Pinus ponderosa at its driest niche edge to investigate whether trees growing near their aridity limit were sensitive to the megadrought climatic pre-conditions, and were capable of informing predictive efforts. During the decade before the megadrought, trees in four populations revealed increases in the cellulose δ13C content of earlywood, latewood, and false latewood, which, based on past studies are correlated with increased intrinsic water-use efficiency. However, radial growth and cellulose δ18O were not sensitive to pre-megadrought conditions. During the 2 decades preceding the megadrought, at all four sites, the changes in δ13C were caused by the high sensitivity of needle carbon and water exchange to drought trends in key winter months, and for three of the four sites during crucial summer months. Such pre-megadrought physiological sensitivity appears to be unique for trees near their arid range limit, as similar patterns were not observed in trees in ten reference sites located along a latitudinal gradient in the same megadrought domain, despite similar drying trends. Our results reveal the utility of tree-ring δ13C to reconstruct spatiotemporal patterns during the organizational phase of a megadrought, demonstrating that trees near the arid boundaries of a species' distribution might be useful in the early detection of long-lasting droughts.

Carbon and oxygen isotope fractionations in tree rings reveal interactions between cambial phenology and seasonal climate.

We developed novel approaches for using the isotope composition of tree-ring subdivisions to study seasonal dynamics in tree-climate relations. Across a 30-year time series, the δ13 C and δ18 O values of the earlywood (EW) cellulose in the annual rings of Pinus ponderosa reflected relatively high intrinsic water-use efficiencies and high evaporative fractionation of 18 O/16 O, respectively, compared with the false latewood (FLW), summerwood (SW), and latewood (LW) subdivisions. This result is counterintuitive, given the spring origins of the EW source water and midsummer origins of the FLW, SW, and LW. With the use of the Craig-Gordon (CG), isotope-climate model revealed that the isotope ratios in all of the ring subdivision are explained by the existence of seasonal lags, lasting several weeks, between the initial formation of tracheids and the production of cellulosic secondary cell walls during maturation. In contrast to some past studies, modification of the CG model according to conventional methods to account for mixing of needle water between fractionated and nonfractionated sources did not improve the accuracy of predictions. Our results reveal new potential in the use of tree-ring isotopes to reconstruct past intra-annual tree-climate relations if lags in cambial phenology are reconciled with isotope ratio observations and included in theoretical treatments.

Disentangling seasonal and interannual legacies from inferred patterns of forest water and carbon cycling using tree-ring stable isotopes.

Tree-ring carbon and oxygen isotope ratios have been used to understand past dynamics in forest carbon and water cycling. Recently, this has been possible for different parts of single growing seasons by isolating anatomical sections within individual annual rings. Uncertainties in this approach are associated with correlated climate legacies that can occur at a higher frequency, such as across successive seasons, or a lower frequency, such as across years. The objective of this study was to gain insight into how legacies affect cross-correlation in the δ13 C and δ18 O isotope ratios in the earlywood (EW) and latewood (LW) fractions of Pinus ponderosa trees at thirteen sites across a latitudinal gradient influenced by the North American Monsoon (NAM) climate system. We observed that δ13 C from EW and LW has significant positive cross-correlations at most sites, whereas EW and LW δ18 O values were cross-correlated at about half the sites. Using combined statistical and mechanistic models, we show that cross-correlations in both δ13 C and δ18 O can be largely explained by a low-frequency (multiple-year) mode that may be associated with long-term climate change. We isolated, and statistically removed, the low-frequency correlation, which resulted in greater geographical differentiation of the EW and LW isotope signals. The remaining higher-frequency (seasonal) cross-correlations between EW and LW isotope ratios were explored using a mechanistic isotope fractionation-climate model. This showed that lower atmospheric vapor pressure deficits associated with monsoon rain increase the EW-LW differentiation for both δ13 C and δ18 O at southern sites, compared to northern sites. Our results support the hypothesis that dominantly unimodal precipitation regimes, such as near the northern boundary of the NAM, are more likely to foster cross-correlations in the isotope signals of EW and LW, potentially due to greater sharing of common carbohydrate and soil water resource pools, compared to southerly sites with bimodal precipitation regimes.

Asian monsoon failure and megadrought during the last millennium.

The Asian monsoon system affects more than half of humanity worldwide, yet the dynamical processes that govern its complex spatiotemporal variability are not sufficiently understood to model and predict its behavior, due in part to inadequate long-term climate observations. Here we present the Monsoon Asia Drought Atlas (MADA), a seasonally resolved gridded spatial reconstruction of Asian monsoon drought and pluvials over the past millennium, derived from a network of tree-ring chronologies. MADA provides the spatiotemporal details of known historic monsoon failures and reveals the occurrence, severity, and fingerprint of previously unknown monsoon megadroughts and their close linkages to large-scale patterns of tropical Indo-Pacific sea surface temperatures. MADA thus provides a long-term context for recent monsoon variability that is critically needed for climate modeling, prediction, and attribution.

Relation of surgeon and hospital volume to processes and outcomes of colorectal cancer surgery.

BACKGROUND: Greater hospital volume has been associated with lower mortality after colorectal cancer surgery. The contribution of surgeon volume to processes and outcomes of care is less well understood. We assessed the relation of surgeon and hospital volume to postoperative and overall mortality, colostomy rates, and use of adjuvant radiation therapy. METHODS: From the California Cancer Registry, we studied 28,644 patients who underwent surgical resection of stage I to III colorectal cancer during 1996 to 1999 and were followed up to 6 years after surgery to assess 30-day postoperative mortality, overall long-term mortality, permanent colostomy, and use of adjuvant radiation therapy. RESULTS: Across decreasing quartiles of hospital and surgeon volume, 30-day postoperative mortality ranged from 2.7% to 4.2% (P < 0.001). Adjusting for age, stage, comorbidity, and median income among patients with colorectal cancer who survived at least 30 days, patients in the lowest quartile of surgeon volume had a higher adjusted overall mortality rate than those in the highest quartile (hazard ratio, 1.16; 95% confidence interval, 1.09-1.24), as did patients in the lowest quartile of hospital volume relative to those treated in the highest quartile (hazard ratio, 1.11; 95% confidence interval, 1.05-1.19). For rectal cancer, adjusted colostomy rates were significantly higher for low-volume surgeons, and the use of adjuvant radiation therapy was significantly lower for low-volume hospitals. CONCLUSIONS: Greater surgeon and hospital volumes were associated with improved outcomes for patients undergoing surgery for colorectal cancer. Further study of processes that led to these differences may improve the quality of colorectal cancer care.

Needle cell elongation and maturation timing derived from pine needle cellulose delta18O.

Estimates of the timing of Pinus arizonica Engelm. needle development in 1998 and 1999 were derived from the leaf-cellulose delta18O of weekly growth increments. Significant correlations were noted between time series of local humidity and leaf-cellulose delta18O for needles growing near Tucson, Arizona. Correlations with temperature were also significant, but much lower, suggesting these variations in cellulose delta18O were determined mostly by changes in humidity. The timing of all significant correlations lags the timing of the appearance of the new needle growth, and is interpreted as indicating 16-23 d were required for cell enlargement in 1998 and 13-17 d in 1999. Similarly, properties of the environmental time series, when significantly correlated, are interpreted as indicating the duration of cellulose deposition (7-27 d in 1998, 13-21 d in 1999). Variations in stable-isotope back diffusion (the Péclet effect) and the synthesis of cellulose using stored photosynthate are discussed as explanations for departures from a Craig and Gordon-type model of leaf water delta18O. The Péclet effect, use of stored photosynthate, and variations in the growing-season source-water delta18O, probably confound the development of a high-resolution paleohumidity proxy from subfossil needle cellulose delta18O in this region.

Asian subgroups and cancer incidence and mortality rates in California.

The objective of this study was to characterize better the cancer burden among Asian subgroups in California. Nearly 3.7 million Asians reside in California, and no other state has as many Asians. Cancer statistics for Asians often are combined with statistics for Pacific Islanders, and rates for subgroups are not often examined, because most states do not have a large enough population. Asians are affected disproportionately by certain cancers, such as stomach and liver cancers. The California Cancer Registry, a population-based cancer registry, has collected data, including race/ethnicity data, since 1988. The 5-year, average, annual, age-adjusted cancer incidence and mortality rates from 1997 through 2001 were calculated for 5 Asian subgroups: Chinese, Filipino, Japanese, Korean, and Vietnamese. Cancer incidence and mortality varied greatly. Incidence rates for all sites combined among males varied from a low of 318.6 per 100,000 for Chinese to a high of 366.0 per 100,000 among Japanese. For females, rates ranged from 236.6 per 100,000 among Koreans to 302.4 per 100,000 among Japanese. Mortality rates also varied by Asian subgroup. Presenting one statistic for Asian/Pacific Islanders did not provide an accurate depiction of the cancer burden among the different Asian subgroups. Acculturation will continue to affect the patterns of cancer incidence among Asian subgroups in California.

Patients' perceptions of quality of care for colorectal cancer by race, ethnicity, and language.

PURPOSE: To identify opportunities for improving care, we evaluated patients' perceptions of the quality of their cancer care by race, ethnicity, and language. PATIENTS AND METHODS: We surveyed a population-based cohort of 1,067 patients with colorectal cancer in northern California approximately 9 months after diagnosis. Adjusting for clinical and demographic factors, mean problem scores were analyzed on a 100-point scale for six domains of care. RESULTS: Mean problem scores were highest for health information (47.8), followed by treatment information (32.3), psychosocial care (31.7), coordination of care (21.3), confidence in providers (13.1), and access to cancer care (12.7). In adjusted comparisons with white patients, African American patients reported more problems with coordination of care (difference, 9.8; P < .001), psychosocial care (difference, 7.2; P = .03), access to care (difference, 6.6; P = .03), and health information (difference, 12.5; P < .001). Asian/Pacific Islander patients reported more problems than did white patients with coordination of care (difference, 13.2; P < .001), access to care (difference, 15.5; P < .001), and health information (difference, 12.6; P = .004). Hispanic patients tended to report more problems with coordination of care (difference, 4.4; P = .06), access to care (difference, 5.8; P = .08), and treatment information (difference, 7.0; P = .06). Non-English-speaking white patients reported more problems than other white patients with coordination of care (difference, 21.9; P < .001), psychosocial care (difference, 16.1; P = .009), access to care (difference, 19.8; P = .003), and treatment information (difference, 17.8; P = .002). Non-English-speaking Hispanic patients reported more problems than other Hispanic patients with confidence in providers (difference, 16.9; P = .01). CONCLUSION: Efforts to improve patients' experiences with cancer care should address disparities by race, ethnicity, and language, particularly in coordination of care, access to care, and the provision of relevant information.

Nonsteroidal anti-inflammatory drug use and breast cancer risk by stage and hormone receptor status.

BACKGROUND: Epidemiologic studies of the association between nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, and breast cancer risk have yielded inconsistent results. We investigated the association of NSAID use with risk of breast cancer in the California Teachers Study cohort, with special attention to risk of specific breast cancer subtypes and to type of NSAID used. METHODS: We analyzed data on 114 460 women in the California Teachers Study cohort who were aged 22 to 85 years and free of breast cancer at baseline in 1995 to 1996. Information on frequency and duration of NSAID use was collected through a self-administered questionnaire. A total of 2391 women were diagnosed with breast cancer during the follow-up period from 1995 to 2001. We used Cox proportional hazards regression to estimate relative risks (RR) and 95% confidence intervals (CI) of breast cancer subtypes with NSAID use. RESULTS: Neither regular use (more than once a week) of any NSAID (aspirin and ibuprofen combined) nor regular use of aspirin was associated with breast cancer risk (RR = 1.09, 95% CI = 0.97 to 1.21 for daily versus no regular use of NSAIDs and RR = 0.98, 95% CI = 0.86 to 1.13 for daily versus no regular use of aspirin). However, long-term (> or = 5 years) daily aspirin users had a non-statistically significant decreased risk of estrogen receptor and progesterone receptor (ER/PR)-positive breast cancer (RR = 0.80, 95% CI = 0.62 to 1.03). In contrast, we observed a statistically significantly increased risk of ER/PR-negative breast cancer with long-term daily use of aspirin (RR = 1.81, 95% CI = 1.12 to 2.92). In this population, 11 fewer ER/PR-positive breast cancer cases and seven excess ER/PR-negative breast cancer cases may be due to daily long-term aspirin use among 2391 breast cancer cases observed over 6 years if the association were proven to be causal. Long-term daily use of ibuprofen was also associated with an increased risk of breast cancer (RR = 1.51, 95% CI = 1.17 to 1.95), particularly of nonlocalized tumors (RR = 1.92, 95% CI = 1.24 to 2.97). If causality were subsequently proven, 16 of the observed 2391 breast cancer cases and 8 of the 713 non-localized breast cancer cases would be attributable to long-term daily use of ibuprofen. CONCLUSIONS: Long-term daily use of NSAIDs was not associated with breast cancer risk overall. Ibuprofen use was associated with an increased risk of breast cancer, and long-term daily aspirin use was associated with an increased risk of ER/PR-negative breast cancer. However, it is not clear if the observed association is causal.

Residential mobility in the California Teachers Study: implications for geographic differences in disease rates.

BACKGROUND: Especially for cancers with long latency periods, such as breast cancer, the issue of residential mobility hinders ecologic analyses seeking to examine the role of environmental contaminants in chronic disease etiology. This study describes and evaluates characteristics associated with residential mobility in a sub-sample of the California Teachers Study (CTS) cohort. METHODS: In 2000, lifetime residential histories were collected for a sub-sample of 328 women enrolled in the CTS; women's degree of residential mobility and associated factors were analyzed. RESULTS: While most women moved many times during their lives (average = 8.9), the average number of years at their residence when they enrolled in the study was reasonably long (15.1 years). Age strongly predicted duration at current residence but was not related to the number of lifetime residences. After adjusting for age, California-born women and women living in high socioeconomic status (SES) neighborhoods were significantly more residentially stable. Agreement between self-reported urbanization of recent residences and that based on census data of the geocoded residences was very good (80% concordant). Among women currently living in urban areas, an average of 43.3 years, or 77%, of their lifetimes were spent in urban residences; among women currently living in a rural area, an average of 37.3 years, or 67% of their lifetimes were spent in rural residences. CONCLUSIONS: This suggests that analyses of incidence rates based on current residence, while not capturing a woman's full exposure history, may reasonably reflect some aspect of longer term chronic exposures, especially those related to urbanization, at least in professional women.

Regional variations in breast cancer among california teachers.

BACKGROUND: Observed regional differences in breast cancer incidence could provide valuable clues to the etiology of this disease. The pattern of historically higher breast cancer rates among residents of California's San Francisco Bay and Southern Coastal areas is evident in the disease experience among members of the California Teachers Study. This large cohort study has followed female professional school employees for cancer incidence since 1995 and has collected extensive information on breast cancer risk factors. METHODS: Between 1996 and 1999, invasive breast cancer was diagnosed in 1562 of the 115,611 cohort members who could be geocoded to a California address in 1995 and who had no previous breast cancer diagnosis. Adjusted hazard rate ratios (HRs) were estimated through multivariate Cox proportional hazards modeling. RESULTS: Rates were higher for cohort members in the San Francisco Bay area (HR = 1.22; 95% confidence interval = 1.06-1.40) and Southern Coastal area (1.16; 1.04-1.30) compared with those in the rest of California. The distributions of variables representing socioeconomic status, urbanization, and personal risk factors were consistent with higher risks for cohort members residing in the San Francisco Bay and Southern Coastal areas. Adjustment for these factors, however, did not explain regional differences in incidence, resulting in HRs that remained elevated for these 2 areas. CONCLUSION: Regional differences in breast cancer incidence in this large, well-defined cohort are not easily explained by known risk factors.

Residential proximity to agricultural pesticide use and incidence of breast cancer in the California Teachers Study cohort.

We examined the association between residential proximity to agricultural pesticide use and breast cancer incidence among members of the California Teachers Study cohort, a large study of professional school employees with extensive information on breast cancer risk factors, followed for cancer incidence since 1995. We identified 1552 invasive breast cancer cases, diagnosed between 1996 and 1999, among 114,835 cohort members. We used California Pesticide Use Reporting data to select pesticides for analysis based on use volume, carcinogenic potential, and exposure potential; a Geographic Information System was used to estimate pesticide applications within a half-mile radius of subjects' residences. We applied Cox proportional hazard models to estimate hazard rate ratios (HR) for selected pesticides, adjusting for age, race, and socioeconomic status. We saw no association between residential proximity to recent agricultural pesticide use and invasive breast cancer incidence. HR estimates for the highest compared to the lowest exposure categories for groups of agents were as follows: probable or likely carcinogens (1.07, 95% confidence interval (CI): 0.86-1.32), possible or suggestive carcinogens (1.06, 95% CI: 0.87-1.29), mammary carcinogens (1.15, 95% CI: 0.90-1.48), and endocrine disruptors (1.03, 95% CI: 0.86-1.25). HR estimates for other groups and individual pesticides did not differ from unity, nor was there a trend for any groupings of or individual pesticides examined. Stratifying by menopausal status or family history of breast cancer did not substantially affect our results. Our analyses suggest that breast cancer incidence is not elevated in areas of recent, high agricultural pesticide use in California.

Stage of breast cancer diagnosis among medically underserved women in California receiving mammography through a state screening program.

OBJECTIVE: This study describes breast cancer stage at diagnosis among California women receiving mammograms through a state-administered screening program in comparison to other California women. METHOD: Linked data from California-administered screening programs and the California Cancer Registry were used to identify participants diagnosed with breast cancer between 1994 and 2000. Logistic regression was used to compare the adjusted likelihood of late stage disease among program participants (categorized into four subgroups based on the timing and frequency of mammograms) to non-participants in California diagnosed during the same time period. RESULTS: Program participants were significantly more likely than non-participants to be diagnosed at late stage (adjusted OR 1.2; 95% CI 1.1, 1.3), with the highest risk occurring among those diagnosed 0-1 months after initial mammogram (adjusted OR 1.8; 95% CI 1.6, 2.1). The stage distribution among regularly screened participants was similar to non-participants (adjusted OR of late stage disease 0.9; 95% CI 0.7, 1.1). CONCLUSIONS: Although program participants were more likely to be diagnosed at late stage than non-participants, their stage distribution was distinctly different according to their pattern of mammography utilization. This likely reflects differential utilization of program diagnostic and screening services, which should be taken into account in program evaluation.

Active smoking, household passive smoking, and breast cancer: evidence from the California Teachers Study.

BACKGROUND: There is great interest in whether exposure to tobacco smoke, a substance containing human carcinogens, may contribute to a woman's risk of developing breast cancer. To date, literature addressing this question has been mixed, and the question has seldom been examined in large prospective study designs. METHODS: In a 1995 baseline survey, 116 544 members of the California Teachers Study (CTS) cohort, with no previous breast cancer diagnosis and living in the state at initial contact, reported their smoking status. From entry into the cohort through 2000, 2005 study participants were newly diagnosed with invasive breast cancer. We estimated hazard ratios (HRs) for breast cancer associated with several active smoking and household passive smoking variables using Cox proportional hazards models. RESULTS: Irrespective of whether we included passive smokers in the reference category, the incidence of breast cancer among current smokers was higher than that among never smokers (HR = 1.32, 95% confidence interval [CI] = 1.10 to 1.57 relative to all never smokers; HR = 1.25, 95% CI = 1.02 to 1.53 relative to only those never smokers who were unexposed to household passive smoking). Among active smokers, breast cancer risks were statistically significantly increased, compared with all never smokers, among women who started smoking at a younger age, who began smoking at least 5 years before their first full-term pregnancy, or who had longer duration or greater intensity of smoking. Current smoking was associated with increased breast cancer risk relative to all nonsmokers in women without a family history of breast cancer but not among women with such a family history. Breast cancer risks among never smokers reporting household passive smoking exposure were not greater than those among never smokers reporting no such exposure. CONCLUSION: Our study provides evidence that active smoking may play a role in breast cancer etiology and suggests that further research into the connection is warranted, especially with respect to genetic susceptibilities.

Relation of hospital volume to colostomy rates and survival for patients with rectal cancer.

BACKGROUND: Postoperative mortality after some types of cancer surgery is inversely related to the number of operations performed at a hospital (i.e., hospital volume). This study assessed the association of hospital volume with colostomy rates and survival for patients with rectal cancer in a large representative cohort identified from the California Cancer Registry. METHODS: We identified 7257 patients diagnosed from January 1, 1994, through December 31, 1997, with stage I-III rectal cancer who underwent surgical resection. Registry data were linked to hospital discharge abstracts and ZIP-code-level data from the 1990 U.S. Census. Associations of hospital volume with permanent colostomy and 30-day mortality were assessed with the Mantel-Haenszel trend test and logistic regression. Overall survival was examined with the Kaplan-Meier method and a multivariable Cox proportional hazards model. Multivariable analyses adjusted for demographic and clinical variables and patient clustering within hospitals. All tests of statistical significance were two-sided. RESULTS: In unadjusted analyses across decreasing quartiles of hospital volume, we observed statistically significant increases in colostomy rates (29.5%, 31.8%, 35.2%, and 36.6%; P<.001) and in 30-day postoperative mortality (1.6%, 1.6%, 2.9%, and 4.8%; P<.001) and a decrease in 2-year survival (83.7%, 83.2%, 80.9%, and 76.6%; P<.001). The adjusted risks of permanent colostomy (odds ratio [OR] = 1.37, 95% confidence interval [CI] = 1.10 to 1.70), 30-day mortality (OR = 2.64, 95% CI = 1.41 to 4.93), and 2-year mortality (hazard ratio = 1.28, 95% CI = 1.15 to 1.44) were greater for patients at hospitals in the lowest volume quartile than for patients at hospitals in the highest volume quartile. Stratification by tumor stage and comorbidity index did not appreciably affect the results. Adjusted colostomy rates varied statistically significantly (P<.001) among individual hospitals independent of volume. CONCLUSIONS: Rectal cancer patients who underwent surgery at high-volume hospitals were less likely to have a permanent colostomy and had better survival rates than those treated in low-volume hospitals. Identifying processes of care that contribute to these differences may improve patients' outcomes in all hospitals.

Validation of self-reported cancers in the California Teachers Study.

Self-reported cancer data from the California Teachers Study were validated by using California Cancer Registry data. The California Teachers Study cohort consists of 133,479 active and retired California teachers. In 1995-1996, data from a mailed questionnaire were linked to the California Cancer Registry data. Sensitivity and specificity of 11 types of cancer were calculated. Multivariate analyses were conducted to evaluate correlates of false-positive and false-negative reporting. Sensitivities showed great variation by cancer site. The highest sensitivities were observed for breast (96.4%) and thyroid (92.9%) cancers, whereas the lowest sensitivities were those for cervical (44.3%), endometrial (69.1%), and other skin (53.6%) cancers. The sensitivities for in situ cancers (at the time of diagnosis) were considerably lower than those for invasive cancers in about half of the cancer types surveyed. The specificities for individual cancer sites ranged from 90% to 99%; the highest were those for lung cancer, leukemia, and Hodgkin's disease (all 99.9%). The lowest specificity was for other skin cancer (90.2%). In situ stage at diagnosis and older age were significantly associated with false-positive reporting. Age and non-White race were associated with false-negative reporting. These findings suggest that the feasibility of using self-reported data without verification in epidemiologic studies of cancer varies by site.

Use of adjuvant chemotherapy and radiation therapy for colorectal cancer in a population-based cohort.

PURPOSE: Randomized trials have demonstrated that adjuvant chemotherapy improves survival for patients with stage III colon cancer and that chemotherapy combined with radiation therapy improves survival for patients with stage II or III rectal cancer. This population-based study was designed to assess use of these treatments in clinical practice. PATIENTS AND METHODS: From the California Cancer Registry, we identified all patients diagnosed during 1996 to 1997 with stage III colon cancer (n = 1,422) and stage II or III rectal cancer (n = 534) in 22 northern California counties. To supplement registry data on adjuvant therapies and ascertain reasons they were not used, we surveyed physicians or reviewed office records for 1,449 patients (74%). RESULTS: Chemotherapy rates varied widely by age from 88% (age < 55 years) to 11% (age >or= 85 years), and radiation therapy varied similarly. Adjusting for demographic, clinical, and hospital characteristics, chemotherapy was used less often among older and unmarried patients, and radiation therapy was used less often among older patients, black patients, and those initially treated in low-volume hospitals. Adjusted rates of chemotherapy varied significantly (P <.01) among individual hospitals: 79% and 51%, respectively, at one SD above and below average (67%). Physicians' reasons for not providing adjuvant therapy included patient refusal (30% for chemotherapy, 22% for radiation therapy), comorbid illness (22% and 14%, respectively), or lack of clinical indication (22% and 45%, respectively). CONCLUSION: Use of adjuvant therapy for colorectal cancer varies substantially by age, race, marital status, hospital volume, and individual hospital, indicating opportunities to improve care. With enhanced data on adjuvant therapies, population-based registries could become a valuable resource for monitoring the quality of cancer care.

Prospective study of hepatitis C viral infection as a risk factor for subsequent B-cell neoplasia.

Several case-control studies have found increased prevalence of hepatitis C virus (HCV) in patients with non-Hodgkin lymphoma (NHL) and other B-cell lymphoproliferative disorders. We examined whether HCV infection preceded the development of these neoplasms in a prospective cohort study of 48 420 individuals in northern California. Stored sera from 95 subjects with NHL (n = 57), multiple myeloma (n = 24), or Hodgkin disease (n = 14) diagnosed a mean of 21 years after phlebotomy were screened for antibodies to HCV as well as viral RNA, based on previous reports of antibody-negative viremia. Sera from 4 cases and one of 95 age-, sex-, and race-matched controls were repeatedly reactive by enzyme immunoassay, but none were confirmed by recombinant immunoblot assay; none of the case sera had HCV RNA by reverse transcription- polymerase chain reaction. Although acquisition in later life cannot be ruled out, these prospective data do not support a substantial role of chronic HCV infection in the etiology of B-cell neoplasia.