Ovarian Cancer
Understanding the Impact of Chronotype Among Ovarian Cancer Survivors

By Catlin Nalley

New data suggests that ovarian cancer survivors with late chronotypes reported higher levels of pain, which was associated with poorer sleep and diet quality as well as higher levels of inflammation and insulin, according to findings presented at the ASCO 2020 Annual Meeting (Abstract 6018).

Chronotype is defined as an individual’s propensity to sleep at a specific time in a 24-hour cycle, and the literature shows that those with late chronotypes are likely to have poorer health outcomes. However, there is limited date when it comes to ovarian cancer.

This lack of knowledge prompted researchers to evaluate a group of ovarian cancer survivors who were enrolled in the Lifestyle Intervention for oVarian cancer Enhanced Survival (LIVES) study. This trial is “testing whether 1,205 women randomized to a diet and physical activity intervention for 24 months will have longer progression-free survival versus an attention control.”

Methods & Findings

In this analysis, researchers sought to determine the association of chronotypes, and patient reported outcomes (PROs), lifestyle behaviors, and biomarkers of metabolic health and inflammation in ovarian cancer survivors post-treatment (≤ 6.5 months). A total subsample of 438 ovarian cancer survivors enrolled in the NRG/GOG-0225 LIVES study with available baseline measures were included.

The investigators determined chronotypes using “self-reported time to bed (early < 9 pm; mid ≥ 9 pm to ≤12 am; late > 12 am) captured through the Pittsburgh Sleep Quality Index and PROs were measured using subscales of the RAND-36 questionnaire.”

Additionally, they used validated questionnaires for diet and physical activity. Biomarkers were collected at routine clinic visits.

When compared to early and mid-chronotypes, reported pain was significantly higher in late chronotypes (P < 0.05). “Total sleep duration was significant between the three chronotypes (P < 0.05) with late chronotype experiencing less sleep (6.77 ± 1.67 hours) than mid chronotype (7.04 ± 1.31 hours) and early chronotype (7.56 ± 1.33 hours),” the study authors reported.

“Higher reported pain was significantly correlated to poorer CRP levels (r = -0.198, P < 0.001), suggesting higher systemic inflammation and poorer blood insulin levels (r = -0.116, P < 0.05) independent of chronotype classification,” researchers wrote.

“We found that the majority of the women in the subsample were in that mid-chronotype range,” noted study author Tracy E Crane, PhD, Shared Resource Co-Director of Behavioral Measurement and Interventions at the University of Arizona Cancer Center. “However, those who were in the late chronotype tended to have a higher BMI and were also more likely to report higher levels of pain. Additionally, we observed that these individuals have poorer sleep and diet quality, as well as higher levels of inflammation.”

Continued Analysis

The researchers will continue to conduct analyses to better understand what impacts this patient population and their outcomes.

“As the trial comes to an end, we’ll begin to look at other factors, including differences between the women who got the intervention versus those who did not,” noted Crane. “Given that these women came on to trial not long after completing treatment, does time play a factor? It could be that, as time goes on, sleep may improve.

“Right now, it's just an association,” she explained. “We don't know if pain is driving why they're going to bed later. As time goes on, we will be able to have a better understanding of causation.

With more data to be explored, Crane hopes they will be able to contribute more robustly to the literature on ovarian cancer and lifestyle behaviors, specifically regarding diet, sleep, and circadian rhythm.

“Modifiable lifestyle behaviors are of interest to patients,” Crane said. “They can also, as the name says, be modified. Therefore, there are changes individuals can make to their daily living that can have a significant impact on their quality of life.

“We need to be thinking about how we can integrate these into ideas into practice,” she concluded. “Even something as simple as when they eat, exercise, or sleep, may actually have significant impact on patient outcomes.”

Catlin Nalley is a contributing writer.