Estimating and modelling cure in population-based cancer studies within the framework of flexible parametric survival models

<p>Abstract</p> <p>Background</p> <p>When the mortality among a cancer patient group returns to the same level as in the general population, that is, the patients no longer experience excess mortality, the patients still alive are considered "statistically cured". Cure models can be used to estimate the cure proportion as well as the survival function of the "uncured". One limitation of parametric cure models is that the functional form of the survival of the "uncured" has to be specified. It can sometimes be hard to find a survival function flexible enough to fit the observed data, for example, when there is high excess hazard within a few months from diagnosis, which is common among older age groups. This has led to the exclusion of older age groups in population-based cancer studies using cure models.</p> <p>Methods</p> <p>Here we have extended the flexible parametric survival model to incorporate cure as a special case to estimate the cure proportion and the survival of the "uncured". Flexible parametric survival models use splines to model the underlying hazard function, and therefore no parametric distribution has to be specified.</p> <p>Results</p> <p>We have compared the fit from standard cure models to our flexible cure model, using data on colon cancer patients in Finland. This new method gives similar results to a standard cure model, when it is reliable, and better fit when the standard cure model gives biased estimates.</p> <p>Conclusions</p> <p>Cure models within the framework of flexible parametric models enables cure modelling when standard models give biased estimates. These flexible cure models enable inclusion of older age groups and can give stage-specific estimates, which is not always possible from parametric cure models.</p

Modelling of amorphous polymer surfaces in computer simulation

We study surface effects in amorphous polymer systems by means of computer simulation. In the framework of molecular dynamics, we present two different methods to prepare such surfaces. {\em Free} surfaces are stabilized solely by van--der--Waals interactions whereas {\em confined} surfaces emerge in the presence of repelling plates. The two models are compared in various computer simulations. For free surfaces, we analyze the migration of end--monomers to the surface. The buildup of density and pressure profiles from zero to their bulk values depends on the surface preparation method. In the case of confined surfaces, we find density and pressure oszillations next to the repelling plates. We investigate the influence of surfaces on the coordination number, on the orientation of single bonds, and on polymer end--to--end vectors. Furthermore, different statistical methods to determine location and width of the surface region for systems of various chain lengths are discussed and applied. We introduce a ``height function'' and show that this method allows to determine average surface profiles only by scanning the outermost layer of monomers.Comment: 23 pages, 12 figure

A multi-state model incorporating estimation of excess hazards and multiple time scales

As cancer patient survival improves, late effects from treatment are becoming the next clinical challenge. Chemotherapy and radiotherapy, for example, potentially increase the risk of both morbidity and mortality from second malignancies and cardiovascular disease. To provide clinically relevant population-level measures of late effects, it is of importance to (1) simultaneously estimate the risks of both morbidity and mortality, (2) partition these risks into the component expected in the absence of cancer and the component due to the cancer and its treatment, and (3) incorporate the multiple time scales of attained age, calendar time, and time since diagnosis. Multi-state models provide a framework for simultaneously studying morbidity and mortality, but do not solve the problem of partitioning the risks. However, this partitioning can be achieved by applying a relative survival framework, by allowing is to directly quantify the excess risk. This paper proposes a combination of these two frameworks, providing one approach to address (1)-(3). Using recently developed methods in multi-state modeling, we incorporate estimation of excess hazards into a multi-state model. Both intermediate and absorbing state risks can be partitioned and different transitions are allowed to have different and/or multiple time scales. We illustrate our approach using data on Hodgkin lymphoma patients and excess risk of diseases of the circulatory system, and provide user-friendly Stata software with accompanying example code

Differences in Management of Older Women Influence Breast Cancer Survival: Results from a Population-Based Database in Sweden

BACKGROUND: Several reports have shown that less aggressive patterns of diagnostic activity and care are provided to elderly breast carcinoma patients. We sought to investigate whether differences in the management of older women with breast cancer are associated with survival. METHODS AND FINDINGS: In an observational study using a population-based clinical breast cancer register of one health-care region in Sweden, we identified 9,059 women aged 50–84 y diagnosed with primary breast cancer between 1992 and 2002. The 5-y relative survival ratio was estimated for patients classified by age group, diagnostic activity, tumor characteristics, and treatment. The 5-y relative survival for breast cancer patients was lower (up to 13%) in women 70–84 y of age compared to women aged 50–69 y, and the difference was most pronounced in stage IIB–III and in the unstaged. Significant differences in disease management were found, as older women had larger tumors, had fewer nodes examined, and did not receive treatment by radiotherapy or by chemotherapy as often as the younger women. Adjustment for diagnostic activity, tumor characteristics, and treatment diminished the relative excess mortality in stages III and in the unstaged, whereas the excess mortality was only marginally affected in stage IIB. CONCLUSIONS: Less diagnostic activity, less aggressive treatment, and later diagnosis in older women are associated with poorer survival. The large differences in treatment of older women are difficult to explain by co-morbidity alone

Progress in Hodgkin lymphoma: a population-based study on patients diagnosed in Sweden from 1973-2009.

To access publisher's full text version of this article. Please click on the hyperlink in Additional Links field.In recent decades, attention has focused on reducing long-term, treatment-related morbidity and mortality in Hodgkin lymphoma (HL). In the present study, we looked for trends in relative survival for all patients diagnosed with HL in Sweden from 1973-2009 (N = 6949; 3985 men and 2964 women; median age, 45 years) and followed up for death until the end of 2010. Patients were categorized into 6 age groups and 5 calendar periods (1973-1979, 1980-1986, 1987-1994, 1994-2000, and 2001-2009). Relative survival improved in all age groups, with the greatest improvement in patients 51-65 years of age (P < .0005). A plateau in relative survival was observed in patients below 65 years of age during the last calendar period, suggesting a reduced long-term, treatment-related mortality. The 10-year relative survival for patients diagnosed in 2000-2009 was 0.95, 0.96, 0.93, 0.80, and 0.44 for the age groups 0-18, 19-35, 36-50, 51-65, and 66-80, respectively. Therefore, despite progress, age at diagnosis remains an important prognostic factor (P < .0005). Advances in therapy for patients with limited and advanced-stage HL have contributed to an increasing cure rate. In addition, our findings support that long-term mortality of HL therapy has decreased. Elderly HL patients still do poorly, and targeted treatment options associated with fewer side effects will advance the clinical HL field.Swedish Cancer Society CAN 2009/1203 Stockholm County Council Karolinska Institutet SLL 20090201 Karolinska Institutet Foundations 2009Fobi007

Patterns of survival among patients with myeloproliferative neoplasms diagnosed in Sweden from 1973 to 2008: a population-based study.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.Reported survival in patients with myeloproliferative neoplasms (MPNs) shows great variation. Patients with primary myelofibrosis (PMF) have substantially reduced life expectancy, whereas patients with polycythemia vera (PV) and essential thrombocythemia (ET) have moderately reduced survival in most, but not all, studies. We conducted a large population-based study to establish patterns of survival in more than 9,000 patients with MPNs. We identified 9,384 patients with MPNs (from the Swedish Cancer Register) diagnosed from 1973 to 2008 (divided into four calendar periods) with follow-up to 2009. Relative survival ratios (RSRs) and excess mortality rate ratios were computed as measures of survival. Patient survival was considerably lower in all MPN subtypes compared with expected survival in the general population, reflected in 10-year RSRs of 0.64 (95% CI, 0.62 to 0.67) in patients with PV, 0.68 (95% CI, 0.64 to 0.71) in those with ET, and 0.21 (95% CI, 0.18 to 0.25) in those with PMF. Excess mortality was observed in patients with any MPN subtype during all four calendar periods (P < .001). Survival improved significantly over time (P < .001); however, the improvement was less pronounced after the year 2000 and was confined to patients with PV and ET. We found patients with any MPN subtype to have significantly reduced life expectancy compared with the general population. The improvement over time is most likely explained by better overall clinical management of patients with MPN. The decreased life expectancy even in the most recent calendar period emphasizes the need for new treatment options for these patients.Swedish Cancer Society CAN 2009/1203 Stockholm County Council SLL 20090201 Karolinska Institutet SLL 20090201 Karolinska Institutet Foundations 2009Fobi0072 Shire Pharmaceuticals Adolf H. Lundin Charitable Foundatio

Dramatically improved survival in multiple myeloma patients in the recent decade: results from a Swedish population-based study.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesUniversity of Iceland Research Fund Icelandic Centre for Research (RANNIS) Landspitali University Hospital Research Fund Karolinska Institutet Foundations Marie Curie CI

Luzp4 defines a new mRNA export pathway in cancer cells

Cancer testis antigens (CTAs) represented a poorly characterized group of proteins whose expression is normally restricted to testis but are frequently up-regulated in cancer cells. Here we show that one CTA, Luzp4, is an mRNA export adaptor. It associates with the TREX mRNA export complex subunit Uap56 and harbours a Uap56 binding motif, conserved in other mRNA export adaptors. Luzp4 binds the principal mRNA export receptor Nxf1, enhances its RNA binding activity and complements Alyref knockdown in vivo. Whilst Luzp4 is up-regulated in a range of tumours, it appears preferentially expressed in melanoma cells where it is required for growth