A recent method of age-standardisation of relative survival ratios for cancer patients does not require calculation of age-specific relative survival ratios, as ratios of age-specific proportions between the standard population and study group at the beginning of the follow-up are used to substitute the original individual observations. This method, however, leads to direct age-standardisation with weights that are different for each patient group if the general population mortality patterns for the groups are different. This is the case in international comparisons, and in comparisons between genders and time periods. The magnitude of the bias caused by the differences in general population mortality is investigated for comparisons involving European countries and the USA. Patients in each country are assumed to have exactly the same age-specific relative survival ratios as those diagnosed in Finland in 1985-2004. An application of a properly functioning age-standardisation method should then give exactly equal age-standardised relative survival ratios for each country. However, the recent method shows substantial differences between countries, with highest relative survival for populations, where the general population mortality in the oldest ages is the highest. This source of error can thus be a serious limitation for the use of the method, and other methods that are available should then be employed.
The study purpose was to assess association of symptoms at screening visits with detection of breast cancer among women aged 50-69 years during the period 2006-2010. Altogether 1.2 million screening visits were made and symptoms (lump, retraction, secretion etc.) were reported either by women or radiographer. Breast cancer risk was calculated for each symptom separately using logistic regression [odds ratio (OR)] and 95% confidence intervals (CIs). Of the 1,198,410 screening visits symptoms were reported in 298,220 (25%) visits. Breast cancer detection rate for women with and without symptoms was 7.8 per 1,000 and 4.7 per 1,000 screening visits, respectively, whereas lump detected 32 cancers per 1,000 screens. Women with lump or retraction had an increased risk of breast cancer, OR?=?6.47, 95% CI 5.89-7.09 and OR?=?2.19, 95% CI 1.92-2.49, respectively. The sensitivity of symptoms in detecting breast carcinoma was 35.5% overall. Individual symptoms sensitivity and specificity ranged from, 0.66 to 14.8% and 87.4 to 99.7%, respectively. Of 5,541 invasive breast cancers, 1,993 (36%) reported symptoms at screen. Breast cancer risk among women with lump or retraction was higher in large size tumors (OR?=?9.20, 95% CI 8.08-10.5) with poorly differentiated grades (OR?=?5.91, 95% CI 5.03-6.94) and regional lymph nodes involvement (OR?=?6.47, 95% CI 5.67-7.38). This study was done in a setting where breast tumors size is generally small, and symptoms sensitivity and specificity in diagnosing breast tumors were limited. Importance of breast cancer symptoms in the cancer prevention and control strategy needs to be evaluated also in other settings.
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The purpose was to evaluate alternative cytological screening methods in population-based screening for cervical cancer up to cancer incidence and mortality outcome. Automation-assisted screening was compared to conventional cytological screening in a randomized design. The study was based on follow-up of 503,391 women invited in the Finnish cervical cancer screening program during 1999-2003. The endpoints were incident cervical cancer, severe intraepithelial neoplasia and deaths from cervical cancer. One third of the women had been randomly allocated to automation-assisted screening and two thirds to conventional cytology. Information on cervical cancer and severe neoplasia were obtained through 1999-2007 from a linkage between screening and cancer registry files. There were altogether 3.2 million woman-years at risk, and the average follow-up time was 6.3 years. There was no difference in the risk of cervical cancer between the automation-assisted and conventional screening methods; the relative risk (RR) of cervical cancer between the study and control arm was 1.00 (95% confidence interval [CI] = 0.76-1.29) among all invited and 1.08 (95% CI = 0.76-1.51) among women who were test negative at entry. Comparing women who were test negative with nonscreened, RR of cervical cancer incidence was 0.26, 95% CI = 0.19-0.36 and of mortality 0.24 (0.13-0.43). Both methods were valid for screening. Because cervical cancer is rare in our country, we cannot rule out small differences between methods. Evidence on alternative methods for cervical cancer screening is increasing and it is thus feasible to evaluate new methods in large-scale population-based screening programs up to cancer outcome.
A new net survival method has been introduced by Pohar Perme et al. (2012 ) and recommended to substitute the relative survival methods in current use for evaluating population-based cancer survival.
The new method is based on the use of continuous follow-up time, and is unbiased only under non-informative censoring of the observed survival. However, the population-based cancer survival is often evaluated based on annually or monthly tabulated follow-up intervals. An empirical investigation based on data from the Finnish Cancer Registry was made into the practical importance of the censoring and the level of data tabulation. A systematic comparison was made against the earlier recommended Ederer II method of relative survival using the two currently available computer programs (Pohar Perme (2013)  and Dickman et al. (2013) ).
With exact or monthly tabulated data, the Pohar-Perme and the Ederer II methods give, on average, results that are at five years of follow-up less than 0.5% units and at 10 and 14 years 1-2% units apart from each other. The Pohar-Perme net survival estimator is prone to random variation and may result in biased estimates when exact follow-up times are not available or follow-up is incomplete. With annually tabulated follow-up times, estimates can deviate substantially from those based on more accurate observations, if the actuarial approach is not used.
At 5 years, both the methods perform well. In longer follow-up, the Pohar-Perme estimates should be interpreted with caution using error margins. The actuarial approach should be preferred, if data are annually tabulated.
To compare the detection rates of precancerous and cancerous cervical lesions by human papillomavirus (HPV) DNA testing and by conventional cytology screening.
Prospective randomised trial. Two cohorts were followed over one screening round of five years, screened initially by primary HPV DNA testing or by primary Pap test.
Population based programme for cervical cancer screening in Finland.
Women aged 25-65 years invited for screening in 2003-07 (101,678 in HPV arm; 101,747 in conventional cytology arm).
Women were randomly allocated (1:1) to primary HPV DNA screening followed by cytology triage if they had positive results, or to primary cytology screening. Screening method was disclosed at the screening visit. Trial personnel involved were aware of all test results.
Cumulative detection rates of cervical intraepithelial neoplasia (CIN), adenocarcinoma in situ (AIS), and invasive cervical cancer before the second screening (after five years) or before 31 December 2008. Lesions detected at screening and during the five year interval were included.
1010 and 701 precancerous or cancerous lesions were detected during an average follow-up of 3.6 years in the HPV and cytology arms, respectively. Among invited women, the hazard ratio was 1.53 (95% confidence interval l.28 to 1.84) for CIN grade 1, 1.54 (1.33 to 1.78) for CIN 2, 1.32 (1.09 to 1.59) for CIN 3 or AIS, and 0.81 (0.48 to 1.37) for cervical cancer. In 25-34 year old participants, the cumulative hazard (or cumulative detection rate) was 0.0057 (0.0045 to 0.0072) for HPV screening versus 0.0046 (0.0035 to 0.0059) for conventional screening; corresponding data for women aged 35 years and older were 0.0022 (0.0019 to 0.0026) and 0.0017 (0.0014 to 0.0021), respectively.
Primary HPV DNA screening detects more cervical lesions than primary cytology within one screening round of five years. Even if the detection rate of CIN 3 or AIS increased in the HPV arm in both age groups, the absolute difference in cumulative rates in women aged 35 years or older was small. By carefully selecting age groups and screening intervals, HPV screening could increase the overall detection rate of cervical precancerous lesions only slightly. However, these findings should be interpreted in the context of the high level of opportunistic screening that occurs in Finland.
International Standard Randomised Controlled Trial ISRCTN23885553.
It is common in population-based cancer registries to use the relative survival ratio to estimate patients' probabilities of surviving if their cancer were the only cause of death. Results from the recently proposed new methods of age-standardisation can be interpreted as ratios between the observed and expected survival proportions. Like the non-standardised ratios, these age-standardised relative survival ratios have, however, the desired probability interpretation only under a specific condition. The condition involved is the survival with respect to other causes up to the given point of follow-up. With different lengths of follow-up, this condition is also different. As a consequence, the non-standardised relative survival ratios and those standardised with the two newest methods produce, for different lengths of follow-up, mutually incomparable estimates with respect to age. Not accounting for this may, for example, lead to erroneous conclusions about the cure of the patients. The traditional method of age-standardisation does not have this problem of incomparability. Results of relative survival analyses of data from the Finnish Cancer Registry are used to illustrate this issue. To avoid overinterpretation and confusion, the different interpretations of the relative survival ratios, both non-standardised and age-standardised, must be known. For example, the very popular cumulative relative survival curves, consisting of consecutive cumulative relative survival ratios, should not be produced for the non-standardised ratios or for ratios age-standardised with the two newest methods. In practical applications, it is crucial to know which method of standardisation, and not only which standard population, has been in use.
The purpose of this study was to assess whether occupational exposure to hydrocarbons in the oil-refining activity increases the risk of kidney cancer.
This case-referent study was nested within the cohort of employees in the oil refinery industry in Finland in 1967 to 1982 (n = 9454). The final data included 30 cases of kidney cancer and 81 age- and sex-matched referents.
There was a threefold increase in the kidney cancer risk for exposure to hydrocarbons in crude oil (odds ratio, 3.1; confidence interval, 1.1 to 8.9; 11 exposed cases). The risk was associated with the highest cumulative exposure category to hydrocarbons in crude oil.
Occupational exposure in oil refining, particularly to crude oil, may increase kidney cancer risk. The study assessed historical exposures; further information needs to be collected for evaluating current exposures.
BACKGROUND: Merkel cell carcinoma (MCC) is a rare malignancy of the skin, and its incidence is reported to be rising. The purpose of this study was to calculate its incidence and survival ratios, and to describe the clinical characteristics of Merkel cell carcinoma patients in Finland. METHODS: We calculated the incidence of MCC based on data from the Finnish Cancer Registry. In addition, patient files from hospitals and primary health care centres were reviewed for detailed data on the treatment and disease recurrence of 181 patients diagnosed with MCC in Finland during 1983-2004, and relative survival ratios were calculated for them. RESULTS: The incidence (per 100,000) of MCC in Finland in 1989-2008 was 0.11 for men and 0.12 for women, adjusted for age to the world standard population. The mean age at diagnosis was 76years (range 27-100), and 69% of the patients were women. The most common site of the primary tumour was the head and neck (53%). No extra benefit was gained from a wide surgical margin (?2cm) compared to a margin of 0.1-0.19cm, but an intralesional excision was more often associated with local recurrence. None of the patients with Stage I-II disease who had received postoperative radiotherapy to the tumour bed had a local recurrence. The 5-year relative survival ratio amongst men was 36% (95% confidence interval 20-54%), and amongst women 69% (56 to -82%). CONCLUSIONS: MCC is a rare disease in Finland, with incidence rates similar to those in the other Nordic countries. Our results support the view that complete excision with clear margins and post operative radiotherapy decrease local recurrences.
The incidence of cancer among the indigenous Sami people of Northern Finland is lower than among the Finnish general population. The survival of Sami cancer patients is not known, and therefore it is the object of this study.
The cohort consisted of 2,091 Sami and 4,161 non-Sami who lived on 31 December 1978 in the two Sami municipalities of Inari and Utsjoki, which are located in Northern Finland and are 300-500 km away from the nearest central hospital. The survival experience of Sami and non-Sami cancer patients diagnosed in this cohort during 1979-2009 was compared with that of the Finnish patients outside the cohort.
The Sami and non-Sami cancer patients were matched to other Finnish cancer patients for gender, age and year of diagnosis and for the site of cancer. An additional matching was done for the stage at diagnosis. Cancer-specific survival analyses were made using the Kaplan-Meier method and Cox regression modelling.
There were 204 Sami and 391 non-Sami cancer cases in the cohort, 20,181 matched controls without matching with stage, and 7,874 stage-matched controls. In the cancer-specific analysis without stage variable, the hazard ratio for Sami was 1.05 (95% confidence interval 0.85-1.30) and for non-Sami 1.02 (0.86-1.20), indicating no difference between the survival of those groups and other patients in Finland. Likewise, when the same was done by also matching the stage, there was no difference in cancer survival.
Long distances to medical care or Sami ethnicity have no influence on the cancer patient survival in Northern Finland.