Survival from cancer of the ovary in England and Wales up to 2001

Abstract

The incidence of ovarian cancer varies widely around the world, with the highest rates in the developed countries of Europe and North America, and the lowest in Africa and Asia (Parkin et al, 2002). In England and Wales, ovarian cancer is the most common gynaecological cancer, and the fourth most common after cancers of the breast, large bowel and lung, representing some 5% of all cancers in women. It is rare in premenopausal women, with less than 10% of cases arising under the age of 45. The pattern of incidence for ovarian cancer with age is similar to that of breast and uterine cancers, and they share some reproductive risk factors. Late menarche, high parity, early menopause and long-term use of combined oral contraceptives all confer a lower risk of ovarian cancer, probably by reducing the number of ovulatory cycles. Incidence in England and Wales has increased gradually since the early 1970s, especially in older women (Coleman et al, 1993), but the upward trend in younger women appears to have reached a plateau by the late 1990s (Quinn et al, 2001). Incidence is 5–10% higher among women in more affluent groups than in the most deprived group, and it increased further in these groups during the 1990s (data not shown). In the late 1990s, about 6000 women were diagnosed with ovarian cancer in England and Wales each year. Ovarian cancer accounts for 4000 deaths a year in England and Wales, about 6% of all cancer deaths in women. In contrast to the increasing trend in incidence, overall age-standardised mortality has fallen slightly over the last decade, but a 20–30% fall in mortality among women under 65 years has been balanced by an increase of about 10% in mortality among older women. Survival from ovarian cancer is the lowest among the gynaecological cancers, because it is often at an advanced stage when diagnosed. Some 81 600 women were registered with an ovarian tumour in England and Wales during the 14-year period 1986–1999, but more than 6000 of these tumours were benign, of uncertain behaviour, or metastatic to the ovary from a primary malignancy elsewhere. Of the 75 800 women resident in England and Wales who were registered with a primary, malignant tumour of the ovary, some 63 800 were included in the analyses (84% of those eligible). One percent of women were excluded because their vital status was not known on 5 November 2002, when the data were extracted for analysis and 10% because their recorded survival time was zero (mainly death certificate only (DCO) cases whose survival time was unknown). A further 3% were excluded because it was not the woman's first primary, invasive cancer, a previous malignancy having been registered for the same woman at some time since 1971. The proportion of cases excluded from analysis as DCOs did not vary by year of diagnosis or by deprivation category. Tumours of the ovary have usually been grouped with those of the Fallopian tube, broad ligament and other uterine adnexa (ICD-9 183, ICD-10 C56–57). Ovarian tumours were only assigned a separate three-digit rubric in the International Classification of Diseases with the introduction of the tenth revision in 1995 (ICD-9 183.0; ICD-10 C56), but in any case almost 99% of the tumours were coded to the ovary, with only about 1% to the Fallopian tube (183.2, C57.0); tumours coded to the broad ligament and other adnexa were extremely rare. As is conventional, therefore, these tumours were included with ovarian cancers in the survival analyses, for consistency in the interpretation of long-term trends. Adenocarcinomas accounted for most tumours that were assigned to a specific morphology, with 39% coded to serous, papillary or mucinous cystadenocarcinoma and 34% to other specific types of adenocarcinoma; 20% were poorly specified carcinomas.