Does the month of diagnosis affect survival of cancer patients?

Seasonal effects on cancer incidence and prognosis

BACKGROUND

It is unknown if the reduction in the expected number of cancer cases diagnosed during Swedish holidays are due to diagnostic delays, how different cancers are affected, and if the season of diagnosis influences long-term cancer survival. We aimed to quantify seasonal trends in incidence and excess mortality for a wide range of malignancies, requiring more or less urgent clinical management.

MATERIAL AND METHODS

This nationwide cohort study included all Swedish residents aged 20-84 in 1990-2019. Incidence and relative survival in pancreatic, colorectal, lung, urothelial, breast, and prostate cancer, together with malignant melanoma, non-Hodgkin lymphoma, and acute leukemia diagnosed during holiday and post-holiday were compared to working (reference) season. Incidence rate ratios (IRR) were estimated using Poisson regression and excess (cancer) mortality rate ratios using flexible parametric models.

RESULTS

We identified 882,980 cancer cases. Incidence declined during holiday season for all malignancies and the IRR ranged from 0.58 (95% CI 0.57-0.59 in breast to 0.92 (95% CI 0.89-0.94) in pancreatic cancer. A post-holiday increase was noted for acute leukemia, pancreatic, and lung cancer. For all malignancies except lung cancer, non-Hodgkin lymphoma, and acute leukemia, the excess mortality at 2 years from diagnosis was higher among those diagnosed during the holiday season. A tendency toward elevated short-term (0.5 years) excess mortality was noted in the post-holiday group, but long-term effects only persisted in breast cancer.

CONCLUSION

This study demonstrates lower holiday detection rates and higher mortality rates in various cancer types diagnosed during holiday season. Healthcare systems should offer a uniform level of cancer care independent of calendar season.

Circannual variation of efficacy outcomes in patients with newly diagnosed metastatic colorectal cancer and treated with first-line chemotherapy

Seasonal variation of baseline diagnosis (or clinical suspect) of stage I-III colorectal cancer patients has been repeatedly reported as an independent variable influencing overall survival. However, data are conflicting and no information is available about such a rhythm in advanced stage patients. To test whether a circannual rhythm of efficacy outcomes can be detected in this setting, we collected data about response rate (RR), progression-free survival (PFS), and overall survival (OS) to first-line chemotherapy of 1610 newly diagnosed metastatic patients treated at four independent centers. Responses to first-line chemotherapy were available for 1495 patients. A strong circannual rhythm in RR was evident, with the higher proportion of responding patients in the subgroup diagnosed in January (acrophase). At the time of data cutoff, 1322 patients progressed and 986 died, with median PFS and OS of 11 and 25.6 months, respectively. A circannual rhythmicity of the proportion of patients progressing at 6 months and surviving at 1 year was demonstrated, with acrophases located both in winter (February and January, respectively), similar to what reported for RR. Several interpretations about the genesis of this cyclic variation could be claimed: the rhythm in sunlight exposure and, as a consequence, of vitamin D serum levels and folate degradation, the variability in toxic effect intensity of chemotherapy, and the rhythm in the biological behavior of tumor cells. This observation is worth of further investigation both in preclinical and in clinical settings in order to better elucidate the underlying mechanisms.

Season of diagnosis and prognosis in breast and prostate cancer

BACKGROUND

Patients with breast or prostate cancer diagnosed during the summer season have been observed to have better survival. The extent to which this is due to biological and/or health care system related factors is unclear.

METHODS

Using the Swedish Cancer Register and clinical databases, we analyzed overall survival by month of diagnosis among the incident cases of breast (n = 89,630) cancer and prostate (n = 72,375) cancer diagnosed from 1960 to 2004. We retrieved data on tumor stage from 1976 for breast cancer and 1997 for prostate cancer. Cox proportional hazards models were used to calculate relative risk of survival by the season of diagnosis.

RESULTS

There was a higher hazard ratio of death in men and women diagnosed with cancer in the summer with a relative hazard of 1.20 (95% confidence interval 1.15-1.25) for July for prostate cancer and 1.14 (95% confidence interval 1.09-1.19) for August for breast cancer when compared to being diagnosed in January. This difference coincided with a lower mean number of cases diagnosed per day, and a higher proportion of advanced cases diagnosed in the summer. This pattern of presentation was stronger in the later years.

CONCLUSION

The difference in stage distribution explains the seasonal variation in prognosis seen in this study. The variation may be because of structure of the health care system and a strong tradition of vacationing from mid June to mid August. Thus, the health care infrastructure and the late presentation of symptomatic disease may influence cancer survival studied by season of diagnosis substantially.

Season, Sun, Sex, and Cervical Cancer

INTRODUCTION

Sunlight's UV B component, a known cellular immunosupressant, carcinogen, and activator of viral infections, is generally seasonally available. Venereal human papillomavirus (HPV) transmission, at least in part, causes cervical cancer. We have previously inspected the monthly rates of venereal HPV infection and sunlight fluency in Southern Holland over 16 consecutive years. Both peak in August with at least 2-fold seasonality. The amount of available sunlight and the rate of Papanicolaou (Pap) smear screen-detected HPV are positively correlated. We now investigate whether premalignant and malignant cervical epithelial changes are also seasonal and related to seasonal sunlight fluency.

METHODS

We have studied >900,000 consecutive, serially independent, interpretable screening Pap smears obtained by a single cervical cancer screening laboratory in Leiden, Holland, during a continuous 16-year span from 1983 through 1998. The average monthly rates of premalignant and malignant epithelial change were inspected and the annual patterns contrasted to the annual pattern of sunlight fluency at this global location and to monthly average HPV infection rate. Because HPV is venereally transmitted, Dutch seasonal sexual behavior was evaluated by assessment of the annual pattern of Dutch conception frequency as a competing cause for cervical cancer seasonality.

RESULTS

(a) Twice as many premalignant and malignant epithelial changes were found among Pap smears obtained in the summer months, with an August peak concurrent with histopathologic evidence of HPV infection and sunlight fluency in Southern Holland. (b) Monthly sunlight fluency is correlated positively with both the monthly rates of Pap smear-detected cervical epithelial dysplasia and carcinomatous histopathology, as well as HPV. (c) Conception frequency, in this location, peaks in Spring not summer, and has a 4.8% annual amplitude.

CONCLUSIONS

(a) Cervical epithelial HPV infection and HPV-induced cervical epithelial dysplasia and carcinomatous change may each be novel sun exposure risks and thereby behaviorably avoidable. (b) Because screening Pap smears uncover many abnormalities that resolve spontaneously (false positives), these data may argue for screening and follow-up Pap smear examinations in seasons other than summer in the Northern Hemisphere, to diminish the false-positive smear rate. Global data are available to confirm and further test each of these conclusions.

Photoperiod modulates melanoma growth in C57BL/6 mice

Seasonal variations can be found in almost any parameter of an organism's biochemistry, physiology, endocrinology, and behaviour. This phenomenon, generally called photoperiodism, results from one of the major functions of the circadian system, i.e. the translation of environmental information into rhythmic intraorganismic signals, which then regulate or influence physiology and pathology. We induced melanoma in three groups of syngeneic C57BL/6 mice synchronised to different photoperiods (8, 12, or 18 h of light within 24-h days) by subcutaneous injections of HFH18 melanoma cell suspensions. All animals from all three photoperiodic groups developed exponentially growing tumors. The average tumor volume on day 31 post injection was significantly smaller in animals exposed to light/dark conditions (LD) 8 : 16 h as compared with animals held in LD 18 : 6 h and intermediate in animals from the equinox group. These results indicate that C57BL/6 mice react to photoperiod, which can exert a significant effect on tumor growth.

Predictability of monthly and yearly rhythms of breast cancer features

In order to evaluate if breast cancer biological characteristics undergo significant menstrual and seasonal variations, we analysed in a consecutive series of 905 breast cancer patients, steroid receptor level (ER and PgR by DCC assay), proliferative activity (3H-Thymidine Labeling Index, 3H-TLI) and size of primary tumour in relation to calendar date and day of menstrual cycle at the time of the surgical procedure. For data analysis, the method of time series construction and classical spectral analyses with Bartlett Kolmogorov-Smirnov test for white noise (BKS test) was utilised. For what concerns menstrual variations, 3H-TLI showed a significant periodicity (t = 0.3146, p < 0.01 by BKS test) with peaks at day 12nd and day 18th; ER showed a significant periodicity (t = 0.3605, p < 0.01 by BKS test) with more evident peak at day 27th; PgR, a significant periodicity (t = 0.160, p = 0.05 by BKS test) with peaks at day 15th and day 24th, similar to that observed for tumour size (t = 0.19, p < 0.05 by BKS test). With respect to yearly fluctuations, 3H-TLI showed only a trend for a significant rhythm (t = 0.16, p = 0.06 by BKS test) with peaks in May and November; ER a significant periodicity (t = 0.2099, p < 0.05 by BKS test) with two evident peaks in January and April; also for PgR a significant periodicity (t = 0.3161, p < 0.05 by BKS test) was demonstrated with a peak in July; finally, tumour size showed a significant rhythm (t = 0.335, p < 0.01) paralleling 3H-TLI behaviour. Finally, the analysis of variance with interaction of menstrual and seasonal timings showed that only the seasonal timing was able to independently influence the 3H-TLI variations (3H-TLI higher in spring). We confirmed that breast biology has significant menstrual and seasonal variations and that the seasonality is probably the timing factor more relevant in periodicity determination.

Seasonal fluctuations in the cervical smear detection rates for (pre)malignant changes and for infections

The detection of diseases can exhibit seasonal fluctuations. This can be studied in cervical smears. Over a 9-year observation span (January 1983-January 1992) a series of 504,093 cervical smears obtained from a routine cytology laboratory in The Netherlands were examined for infections (monilia, trichomonas, actinomyces, human papilloma virus [HPV], chlamydia, and herpes) as well as for mild, moderate, and severe dysplasias, carcinoma in situ, and squamous carcinoma. Statistical analysis (principal component analysis) demonstrates clear seasonal rhythms in the detection of infections as well as in precursor lesions. These findings suggest that we are dealing with "true" detection rhythms. For the detection of (pre)malignancy and HPV, yearly fluctuations in women being screened might be the explanation for our observations.

Birth season and breast cancer risk in Japan

Recent studies suggest that prenatal or early post-natal factors may influence future breast cancer risk. To investigate whether month of birth is a risk factor for breast cancer, we analyzed the distribution of month of birth for 81,162 women died of breast cancer and 1,334,650 women died of cancers at all sites, who were reported to the Ministry of Health and Welfare from 1972-90 in Japan. After considering each birth year seasonal variations in month of birth were not shown statistically significant in any age-group through using chi 2 test (df = 11). The negative results were also confirmed in residential area and period category.

The influence of season, photoperiod, and pineal melatonin on immune function

In addition to the well-documented seasonal cycles of mating and birth, there are also significant seasonal cycles of illness and death among many animal populations. Challenging winter conditions (i.e., low ambient temperature and decreased food availability) can directly induce death via hypothermia, starvation, or shock. Coping with these challenges can also indirectly increase morbidity and mortality by increasing glucocorticoid secretion, which can compromise immune function. Many environmental challenges are recurrent and thus predictable; animals could enhance survival, and presumably increase fitness, if they could anticipate immunologically challenging conditions in order to cope with these seasonal threats to health. The annual cycle of changing photoperiod provides an accurate indicator of time of year and thus allows immunological adjustments prior to the deterioration of conditions. Pineal melatonin codes day length information. Short day lengths enhance several aspects of immune function in laboratory studies, and melatonin appears to mediate many of the enhanced immunological effects of photoperiod. Generally, field studies report compromised immune function during the short days of autumn and winter. The conflict between laboratory and field data is addressed with a multifactor approach. The evidence for seasonal fluctuations in lymphatic tissue size and structure, as well as immune function and disease processes, is reviewed. The role of pineal melatonin and the hormones regulated by melatonin is discussed from an evolutionary and adaptive functional perspective. Finally, the clinically significance of seasonal fluctuations in immune function is presented. Taken together, it appears that seasonal fluctuations in immune parameters, mediated by melatonin, could have profound effects on the etiology and progression of diseases in humans and nonhuman animals. An adaptive functional perspective is critical to gain insights into the interaction among melatonin, immune function, and disease processes.