Socioeconomic determinants of cancer risk, detection, and outcome in the Netherlands since 1990

The subject of this thesis is the association between socioeconomic status (SES) and cancer detection and outcome in the Netherlands. Both a description of and explanation for variation in incidence, detection, staging, treatment, survival and health-related quality of life of cancer by SES are given. The studies reported in this thesis can be placed both within the broader framework of research on socioeconomic inequalities in health as well as within the narrower framework of research on socioeconomic inequalities in cancer. The methods and study settings are described, followed by the aims of this thesis

Educational inequalities in cancer survival: A role for comorbidities and health behaviours?

Aim: To describe educational inequalities in cancer survival and to what extent these can be explained by comorbidity and health behaviours (smoking, physical activity and alcohol consumption). Methods: The GLOBE study sent postal questionnaires to individuals in The Netherlands in 1991 resulting in 18 973 respondents (response 70%). Questions were asked on education, health and health-related behaviours. Participants were linked for cancer diagnosis (1991-2008), comorbidity and survival (up to 2010) with the population-based Eindhoven Cancer Registry; 1127 tumours were included in the analyses. Results: 5-year crude survival was best in highly educated patients as compared with low educated patients for all cancers combined: 49% versus 32% in male subjects (log rank: p<0.0001), 65% versus 49% in female subjects (p=0.0001). Compared with highly educated, low educated prostate cancer patients had an increased risk of death (HR 2.9 (95% CI 1.7 to 5.1), adjusted for age, stage and year). No or inconsistent associations between educational level and risk of death were seen in multivariable analyses for breast, colon and non-small cell lung cancer. Although survival in prostate cancer patients was affected by comorbidities (HR2_vs_0_comorbidities: 2.6 (1.5 to 4.4)), physical activity (HRno/little_vs__moderate_physical__activity: 2.0 (1.2 to 3.4)) and smoking (HRcurrent_vs_never_smokers: 2.6 (1.0-6.8)), these did not contribute to educat

Small but significant socioeconomic inequalities in axillary staging and treatment of breast cancer in the Netherlands

Background: The use of sentinel node biopsy (SNB), lymph node dissection, breast-conserving surgery, radiotherapy, chemotherapy and hormonal treatment for breast cancer was evaluated in relation to socioeconomic status (SES) in the Netherlands, where access to care was assumed to be equal. Methods: Female breast cancer patients diagnosed between 1994 and 2008 were selected from the nationwide population-based Netherlands Cancer Registry (N=176 505). Socioeconomic status was assessed based on income, employment and education at postal code level. Multivariable models included age, year of diagnosis and stage. Results: Sentinal node biopsy was less often applied in high-SES patients (multivariable analyses, ≤49 years: odds ratio (OR) 0.70 (95% CI: 0.56-0.89); 50-75 years: 0.85 (0.73-0.99)). Additionally, lymph node dissection was less common in low-SES patients aged ≥76 years (OR 1.34 (0.95-1.89)). Socioeconomic status-related differences in treatment were only significant in the age group 50-75 years. High-SES women with stage T1-2 were more likely to undergo breast-conserving surgery (radiotherapy) (OR 1.15 (1.09-1.22) and OR 1.16 (1.09-1.22), respectively). Chemotherapy use among node-positive patients was higher in the high-SES group, but was not significant in multivariable analysis. Hormonal therapy was not related to SES. Conclusion: Small but significant differences were observed in the use of SNB, lymph node dissection and breast-conserving surgery according to SES in Dutch breast cancer patients despite assumed equal access to health care

Melanoma in older patients: declining gap in survival between younger and older patients with melanoma

Background: Older people have the highest incidence of melanoma and the population in most Western countries is ageing. We evaluated how the gap in incidence and survival between younger and older patients has developed during the past decades.Material and methods: All patients diagnosed with cutaneous melanoma between 1989 and 2015 (n = 84,827) were identified from the Netherlands Cancer Registry. Elderly were defined as aged ≥70 years. Differences in patient and tumor characteristics were described, age-specific incidence rates were calculated, and relative survival (RS) and multivariable analyses estimating the Relative Excess Rate of dying (RER) were conductedResults: In older men, the melanoma age-standardized incidence increased from 18 to 103/100,000 person-years (py) between 1989 and 2015 and in older women from 23 to 70/100,000 py. In younger men and women, it increased from 8 to 21 and from 13 to 28/100,000 py, respectively. Median Breslow thickness declined from 1.8 to 1.1 mm and from 1.6 to 1.1 mm in older men and women (2003 versus 2015), and from 1.1 to 0.9 mm and 0.9 to 0.8 mm in younger men and women. In older men, 5-year RS increased from 67% (95% CI: 63%-72%) in 1989-1997 to 85% (95% CI: 83%-87%) in 2007-2015 and in older women from 81% (95% CI: 78%-85%) to 89% (95% CI: 87%-91%). In younger men and women, RS increased from 82% (95% CI: 81%-83%) to 90% (95% CI: 90%-91%) and from 92% (95% CI: 92%-93%) to 96% (95% CI: 95%-96%). After case-mix correction , older men and women no longer showed an improved survival over time (RER 2010-2015 versus 2003-2009: 0.97; 95% CI: 0.81-1.16 and 0.95; 95% CI: 0.79-1.16). Whereas in younger men and women survival remained improved (RER 0.75; 95% CI: 0.67-0.83 and 0.77; 95%CI: 0.67-0.89).Conclusion: The gap in melanoma incidence between younger and older peopl

Surgery for unresectable stage IIIC and IV melanoma in the era of new systemic therapy

Opportunities for surgical treatment in metastatic melanoma patients have re-emerged due to the development of novel systemic therapeutics over the past decade. The aim of this study is to present data on outcomes of surgery in patients with unresectable stage IIIC and IV melanoma, who have previously been treated with immunotherapy or targeted therapy. Data was extracted from the Dutch Melanoma Treatment Registry (DMTR) on 154 patients obtaining disease control to systemic therapy and undergoing subsequent surgery. Disease control was defined as a complete response (CR), which was seen in 3.2% of patients; a partial response (PR), seen in 46.1% of patients; or stable disease (SD), seen in 44.2% of patients. At a median follow-up of 10.0 months (interquartile range 4-22) after surgery, the median overall survival (OS) had not been reached in our cohort and median progression-free survival (PFS) was 9.0 months (95% CI 6.3-11.7). A CR or PR at first follow-up after surgery was associated with both a better OS and PFS compared to stable or progressive disease (p < 0.001). We conclude that selected patients can benefit from surgery after achieving disease control with systemic therapy

Risk of diabetes after para-aortic radiation for testicular cancer

Background: While the risk of diabetes is increased following radiation exposure to the pancreas among childhood cancer survivors, its association among testicular cancer (TC) survivors has not been investigated. Methods: Diabetes risk was studied in 2998 1-year TC survivors treated before 50 years of age with orchidectomy with/without radiotherapy between 1976 and 2007. Diabetes incidence was compared with general population rates. Treatment-specific risk of diabetes was assessed using a case–cohort design. Results: With a median follow-up of 13.4 years, 161 TC survivors were diagnosed with diabetes. Diabetes risk was not increased compared to general population rates (standardised incidence ratios (SIR): 0.9; 95% confidence interval (95% CI): 0.7–1.1). Adjusted for age, para-aortic radiotherapy was associated with a 1.66-fold (95% CI: 1.05–2.62) increased diabetes risk compared to no radiotherapy. The excess hazard increased with 0.31 with every 10 Gy increase in the prescribed radiation dose (95% CI: 0.11–0.51, P = 0.003, adjusted for age and BMI); restricted to irradiated patients the excess hazard increased with 0.33 (95% CI: −0.14 to 0.81, P = 0.169) with every 10 Gy increase in radiation dose. Conclusion: Compared to surgery only, para-aortic irradiation is associated with increased diabetes risk among TC survivors

Vemurafenib plus cobimetinib in unresectable stage IIIc or stage IV melanoma

Background: In patients with BRAFV600 mutated unresectable stage IIIc or metastatic melanoma, molecular targeted therapy with combined BRAF/MEK-inhibitor vemurafenib plus cobimetinib has shown a significantly improved progression-free survival and overall survival compared to treatment with vemurafenib alone. Nevertheless, the majority of BRAFV600 mutation-positive melanoma patients will eventually develop resistance to treatment. Molecular imaging with 18F-Fluorodeoxyglucose (18F-FDG) PET has been used to monitor response to vemurafenib in some BRAFV600 mutated metastatic melanoma patients, showing a rapid decline of 18F-FDG uptake within 2 weeks following treatment. Furthermore, preliminary results suggest that metabolic alterations might predict the development of resistance to treatment. 18F-Fluoro-3'-deoxy-3'L-fluorothymidine (18F-FLT), a PET-tracer visualizing proliferation, might be more suitable to predict response or resistance to therapy than 18F-FDG. Methods: This phase II, open-label, multicenter study evaluates whether metabolic response to treatment with vemurafenib plus cobimetinib in the first 7 weeks as assessed by 18F-FDG/18F-FLT PET can predict progression-free survival and whether early changes in 18F-FDG/18F-FLT can be used for early detection of treatment response compared to standard response assessment with RECISTv1.1 ceCT at 7 weeks. Ninety patients with BRAFV600E/K mutated unresectable stage IIIc/IV melanoma will be included. Prior to and during treatment all patients will undergo 18F-FDG PET/CT and in 25 patients additional 18F-FLT PET/CT is performed. Histopathological tumor characterization is assessed in a subset of 40 patients to unravel mechanisms of resistance. Furthermore, in all patients, blood samples are taken for pharmacokinetic analysis of vemurafenib/cobimetinib. Outcomes are correlated with PET/CT-imaging and therapy response.

Lower risk of severe checkpoint inhibitor toxicity in more advanced disease

Background Immune checkpoint inhibitor (ICI) can cause severe and sometimes fatal immune-related adverse events (irAEs). Since these irAEs mimick immunological disease, a female predominance has been speculated on. Nevertheless, no demographic or tumour-related factors associated with an increased risk of irAEs have been identified until now. Methods Risk ratios of severe (grade ≥3) irAEs for age, sex, WHO performance status, number of comorbidities, stage of disease, number of metastases and serum lactate dehydrogenases (LDH) were estimated using data from anti-PD1-treated patients with advanced melanoma in the prospective nationwide Dutch Melanoma Treatment Registry. Results 111 (11%) out of 819 anti-programmed cell death 1 treated patients experienced severe irAEs. Patients with non-lung visceral metastases (stage IV M1c or higher) less often experienced severe irAEs (11%) compared with patients with only lung and/or lymph node/soft tissue involvement (stage IV M1b or lower; 19%; adjusted risk ratio (RR adj) 0.63; 95% CI 0.41 to 0.94). Patients with LDH of more than two times upper limit of normal had a non-significantly lower risk of developing severe irAEs than those with normal LDH (RR adj 0.65; 95% CI 0.20 to 2.13). None of the other variables were associated with severe irAEs. Conclusion In patients with melanoma, more advanced disease is associated with a lower rate of severe irAEs. No association with sex was found

First-line BRAF/MEK inhibitors versus anti-PD-1 monotherapy in BRAFV600-mutant advanced melanoma patients: a propensity-matched survival analysis

Background: Anti-PD-1 antibodies and BRAF/MEK inhibitors are the two main groups of systemic therapy in the treatment of BRAFV600-mutant advanced melanoma. Until now, data are inconclusive on which therapy to use as first-line treatment. The aim of this study was to use propensity score matching to compare first-line anti-PD-1 monotherapy vs. BRAF/MEK inhibitors in advanced BRAFV600-mutant melanoma patients. Methods: We selected patients diagnosed between 2014 and 2017 with advanced melanoma and a known BRAFV600-mutation treated with first-line BRAF/MEK inhibitors or anti-PD-1 antibodies, registered in the Dutch Melanoma Treatment Registry. Patients were matched based on their propensity scores using the nearest neighbour and the optimal matching method. Results: Between 2014 and 2017, a total of 330 and 254 advanced melanoma patients received BRAF/MEK inhibitors and anti-PD-1 monotherapy as first-line systemic therapy. In the matched cohort, patients receiving anti-PD-1 antibodies as a first-line treatment had a higher median and 2-year overall survival compared to patients treated with first-line BRAF/MEK inhibitors, 42.3 months (95% CI: 37.3-NE) vs. 19.8 months (95% CI: 16.7–24.3) and 85.4% (95% CI: 58.1–73.6) vs. 41.7% (95% CI: 34.2–51.0). Conclusions: Our data suggest that in the matched BRAFV600-mutant advanced melanoma patients, anti-PD-1 monotherapy is the preferred first-line treatment in patients with relatively favourable patient and tumour characteristics

Real-world outcomes of advanced melanoma patients not represented in phase III trials

The aim was to provide evidence on systemically treated patients with advanced melanoma not represented in phase III trials to support clinical decision-making. Analysis were performed on advanced melanoma patients diagnosed between 2014 and 2017 in the Netherlands, treated with immune- or targeted therapy, who met ≥1 trial exclusion criteria. These criteria were derived from the KEYNOTE-006 and CHECKMATE-067/-066 phase III trials. Prognostic importance of factors associated with overall survival (OS) was assessed with the Kaplan-Meier method, Cox models, predicted OS probabilities of prognostic subgroups and a conditional inference survival tree (CIST). A nationwide population-based registry was used as data source. Of 2536 systemically treated patients with advanced melanoma, 1004 (40%) patients were ineligible for phase IIII trials. Ineligible patients had a poorer median OS (mOS) compared to eligible patients (8.8 vs 23 months). Eligibility criteria strongly associated with OS in systemically treated ineligible patients were Eastern Cooperative Oncology Group Performance Score (ECOG PS) ≥2, brain metastases (BM) and lactate dehydrogenase (LDH) of >500 U/L. Patients with ECOG PS of ≥2 with or without symptomatic BM had a predicted mOS of 6.5 and 11.3 months and a 3-year survival probability of 9.3% and 23.6%, respectively. The CIST showed the strongest prognostic covariate for survival was LDH, followed by ECOG PS. The prognosis of patients with LDH of >500 U/L is poor, but long-term survival is possible. The prognosis of ineligible patients with advanced melanoma in real-world was very heterogeneous and highly dependent on LDH value, ECOG PS and symptomatic BM