Prostate cancer-specific survival among warfarin users in the Finnish Randomized Study of Screening for Prostate Cancer

Survival outcomes with warfarin compared with direct oral anticoagulants in cancer-associated venous thromboembolism in the United States: A population-based cohort study

BACKGROUND

Direct oral anticoagulants (DOACs) have comparable efficacy with low-molecular-weight heparin (LMWH) for the treatment of cancer-associated venous thromboembolism (VTE). Whether there is a mortality benefit of DOACs compared with warfarin in the management of VTE in cancer is not established.

METHODS AND FINDINGS

Utilizing the United States' Surveillance, Epidemiology, and End Results (SEER)-Medicare linked databases from 2012 through 2016, we analyzed overall survival in individuals diagnosed with a primary gastric, colorectal, pancreas, lung, ovarian, or brain cancer and VTE who received a prescription of DOAC or warfarin within 30 days of VTE diagnosis. Patients were matched 1:2 (DOAC to warfarin) through exact matching for cancer stage and propensity score matching for age, cancer site, cancer stage, and time interval from cancer to VTE diagnosis. The analysis identified 4,274 patients who received a DOAC or warfarin for the treatment of VTE within 30 days of cancer diagnosis (1,348 in DOAC group and 2,926 in warfarin group). Patients were of median age 75 years and 56% female. Within the DOAC group, 1,188 (88%) received rivaroxaban, and 160 (12%) received apixaban. With a median follow-up of 41 months, warfarin was associated with a statistically significantly higher overall survival compared to DOACs (median overall survival 12.0 months [95% confidence interval (CI): 10.9 to 13.5] versus 9.9 months [95% CI: 8.4 to 11.2]; hazard ratio (HR) 0.85; 95% CI: 0.78 to 0.91; p < 0.001). Observed differences in survival were consistent across subgroups of cancer sites, cancer stages, and type of VTE. The study limitations include retrospective design with potential for unaccounted confounders along with issues of generalizability beyond the cancer diagnoses studied.

CONCLUSIONS

In this analysis of a population-based registry, warfarin was associated with prolonged overall survival compared to DOACs for treatment of cancer-associated VTE.

The impact of warfarin on overall survival in cancer patients

Venous thromboembolism (VTE) is a common complication in patients with cancer. Warfarin has largely been replaced by low-molecular-weight heparin (LMWHs) and direct oral anticoagulants (DOACs) as the standard of care in cancer-associated VTE. The survival benefit of these anticoagulants over warfarin in the cancer population was not demonstrated in clinical trials, possibly due to insufficient sample size and limited follow-up duration. There are emerging population-based studies suggesting that warfarin may be associated with improved overall survival in cancers and may have a protective effect against certain types of cancers. Warfarin may exert its anti-neoplastic properties through both coagulation pathway -dependent and -independent mechanisms, the latter of which are mediated by inhibition of the Gas6-AXL signaling pathway. Further research should emphasize on identifying clinical and laboratory predictors of beneficial effects of warfarin. In this review article, we summarize and update the current evidence regarding the potential impact of warfarin on the overall survival of cancer patients and incidence of cancer, as well as review the potential mechanism of such effect and future perspectives.

Overall survival with warfarin vs. low-molecular-weight heparin in cancer-associated thrombosis

BACKGROUND

When compared with warfarin, low-molecular-weight heparin (LMWH) reduces the incidence of recurrent venous thromboembolism (VTE) in cancer. However, a survival benefit of LMWH over warfarin for the treatment of cancer-associated VTE has not been established.

METHODS

Using the Surveillance, Epidemiology and End Results and Medicare linked database from 2007 through 2016, we identified Medicare beneficiaries (aged ≥66 years) who were: (1) diagnosed with primary gastric, colorectal, pancreatic, lung, ovarian, or brain cancer; (2) diagnosed with cancer-associated VTE; and (3) prescribed LMWH or warfarin within 30 days. The primary outcome was overall survival (OS). Patients were matched 1:1 using exact matching for cancer stage and propensity score matching for cancer diagnosis, age, year of VTE, and time from cancer diagnosis to index VTE. Cox proportional-hazards regression was performed to estimate hazard ratios (HR) and 95% confidence intervals (95% CI).

RESULTS

A total of 9706 patients were included. Warfarin was associated with a significant improvement in OS compared with LMWH (median OS, 9.8 months [95% CI, 9.1-10.4] vs. 7.2 months [95% CI, 6.8-7.8]; HR, 0.86; 95% CI 0.83-0.90; p < .001). The survival advantage was most pronounced in pancreatic (HR 0.82 [95% CI, 0.74-0.90], p < .001) and gastric cancers (HR 0.82 [95% CI, 0.68-0.98], p = .03). The observed differences in survival were consistent across subgroups including cancer stage, age, comorbidity burden, and year of VTE.

CONCLUSIONS

In this population-based study, warfarin was associated with improved OS compared with LMWH for the treatment of cancer-associated VTE.

Anticoagulants and cancer mortality in the Finnish randomized study of screening for prostate cancer

PURPOSE

Anticoagulants may reduce mortality of cancer patients, though the evidence remains controversial. We studied the association between different anticoagulants and cancer death.

METHODS

All anticoagulant use during 1995-2015 was analyzed among 75,336 men in the Finnish Randomized Study of Screening for Prostate Cancer. Men with prevalent cancer were excluded. Multivariable Cox regression was performed to compare risk of death from any cancer and disease-specific death from 9 specific cancer types between (1) anticoagulant users overall and (2) warfarin users compared to anticoagulant non-users and (3) warfarin or (4) low-molecular-weight heparins (LMWH) compared to users of other anticoagulants. Medication use was analyzed as time-dependent variable to minimize immortal time bias. 1-, 2- and 3-year lag-time analyses were performed.

RESULTS

During a median follow-up of 17.2 years, a total of 27,233 men died of whom 8033 with cancer as the primary cause of death. In total, 32,628 men (43%) used anticoagulants. Any anticoagulant use was associated with an increased risk of cancer death (HR = 2.50, 95% CI 2.37-2.64) compared to non-users. Risk was similar independent of the amount, duration, or intensity of use. The risk increase was observed both among warfarin and LMWH users, although not as strong in warfarin users. Additionally, cancer-specific risks of death were similar to overall cancer mortality in all anticoagulant categories.

CONCLUSION

Our study does not support reduced cancer mortality among anticoagulant users. Future studies on drug use and cancer mortality should be adjusted for anticoagulants as they are associated with significantly higher risk of cancer death.

Single-cell Wnt signaling niches maintain stemness of alveolar type 2 cells

Alveoli, the lung's respiratory units, are tiny sacs where oxygen enters the bloodstream. They are lined by flat alveolar type 1 (AT1) cells, which mediate gas exchange, and AT2 cells, which secrete surfactant. Rare AT2s also function as alveolar stem cells. We show that AT2 lung stem cells display active Wnt signaling, and many of them are near single, Wnt-expressing fibroblasts. Blocking Wnt secretion depletes these stem cells. Daughter cells leaving the Wnt niche transdifferentiate into AT1s: Maintaining Wnt signaling prevents transdifferentiation, whereas abrogating Wnt signaling promotes it. Injury induces AT2 autocrine Wnts, recruiting "bulk" AT2s as progenitors. Thus, individual AT2 stem cells reside in single-cell fibroblast niches providing juxtacrine Wnts that maintain them, whereas injury induces autocrine Wnts that transiently expand the progenitor pool. This simple niche maintains the gas exchange surface and is coopted in cancer.

Effects of warfarin on biological processes other than haemostasis: A review

Warfarin is the world's most widely used anticoagulant drug. Its anticoagulant activity is based on the inhibition of the vitamin K-dependent (VKD) step in the complete synthesis of a number of blood coagulation factors that are required for normal blood coagulation. Warfarin also affects synthesis of VKD proteins not related to haemostasis including those involved in bone growth and vascular calcification. Antithrombotic activity of warfarin is considered responsible for some aspects of its anti-tumour activity of warfarin. Some aspects of activities against tumours seem not to be related to haemostasis and included effects of warfarin on non-haemostatic VKD proteins as well as those not related to VKD proteins. Inflammatory/immunomodulatory effects of warfarin indicate much broader potential of action of this drug both in physiological and pathological processes. This review provides an overview of the published data dealing with the effects of warfarin on biological processes other than haemostasis.