Ovarian cancer
The incidence of ovarian, fallopian tube and peritoneal cancer (collectively referred to as ovarian cancer) has shown a decline in recent years for women between 50 and 69 years, but has remained stable in the age group over 70 years.
Mortality has declined over the past 40 years for all age groups. Borderline tumours more often affect younger women (median age 55 years), while ovarian cancer affects older women to a greater extent (median age 66 years). The majority of women have had symptoms before going to a doctor (81 per cent of women in 2022).
Cancer of the surface layer of the ovaries is often detected late in the disease course because the symptoms are diffuse, and the disease is thus difficult to detect. 70 per cent of women have metastasis at the time of diagnosis. The degree of spread is important for the treatment that can be offered and also for the patient's prognosis.
Risk factors
The cause of cancer is usually not known, but there are certain factors that can increase the risk of ovarian cancer.
Ovarian cancer occurs more often in women who have not given birth than in women who have gone through childbirth.
Early menstruation and/or late menopause increase the risk. This suggests that the sex hormones and the number of ovulations a woman undergoes may have an impact.
Some scientific studies show that some types of endometriosis (the same tissue that is inside the lining of the uterus) is outside the uterus, such as in the ovaries and fallopian tubes. This can give a slightly elevated chance of getting this type of cancer.
It may appear that tall women are more likely to get the disease than low ones. The association seems to be strongest in women before menopause.
Radiation therapy for previous cancers, and women who have previously had breast cancer are at higher risk.
Between 5 and 15 percent of all cases are due to inheritance.
Source: helsenorge.no
New cases
506 women were diagnosed with ovarian cancer in Norway in 2022. The number of cases per 100,000 person-years is 16.7.
In the period 2018-2022, 20.2 per cent of cases were detected at an early, local stage, while 8.3 per cent were detected in a regional stage. 65.7 per cent had distant metastasis at the time of diagnosis, while only 5.9 per cent had an unknown stage at diagnosis.
Aging
The median age for ovarian cancer is 68 years, which means that half of all those diagnosed are over 68 years of age.
Age distribution for women in Norway with ovarian cancer or borderline tumors in 2021. From Fig. 3.4 in the Annual Report of the National Quality Registry for Gynecological Cancer 2022. (Norwegian only)
Here it can be seen that the age distribution of borderline tumours differs somewhat from the more aggressive tumours in that they arise at a somewhat younger age. In 2022, the median age for ovarian cancer was 68 years, while the median age for borderline tumors was 55 years. This corresponds with the figures from the previous annual reports. It is already known that borderline tumours affect women at a younger age than the more aggressive tumours.
Survival
Five-year relative survival (the proportion who survive 5 years, adjusted for survival in the general population) of ovarian cancer is 51.2 per cent. The survival rate for patients with distant metastasis is significantly lower, at 37.9 percent.
Results from the annual report for the National Quality Registry for Gynecological Cancer 2022 (Gynaecological Cancer Registry, Norwegian only) show long-term effects of treatment for ovarian, fallopian tube and peritoneal cancer, and that 5-year relative survival has increased in all age groups since 1980.
5-year relative survival for ovarian cancer overall and for different age groups from 1980 to 2022. From Fig. 3.31 in the Annual Report of the Gyn Cancer Registry 2022. (Norwegian only)
The figure sheds light on the long-term effects of treatment for ovarian cancer and shows that 5-year relative survival has increased in all age groups since 1980. For all age groups combined, an increase can be seen from 31.1 per cent in the first period to 50.9 per cent in the last period. This is an increase of 19.8 percentage points. There has been a steady increase in survival in all age groups.
By comparison, statistics from NORDCAN show that 5-year relative survival in Denmark and Sweden in the period 2016–2020 was 43.9 per cent and 52.9 per cent respectively. These constituted extremes in survival among the Nor- dian countries during the period.
Ovarian cancer survivors
The number of cancer survivors with ovarian cancer is 5,248 as of 12/31/2022. 2,625 of these were diagnosed more than 10 years ago.
Number of deaths
316 women died of ovarian cancer in Norway in 2021.
Mortality rates for ovarian cancer in different age groups from 1960 to 2021. From Fig. 3.27 in the Annual Report of the Gyn Cancer Registry 2022. (Norwegian only)
The figure shows that the two youngest age groups have had a slight decline in mortality during the entire period, while in the oldest group we can see an increase in mortality from 1960 to the mid-1990s, with a subsequent stabilisation in the last period. The decline/stabilisation of mortality in the various age groups in recent decades is most likely due to better treatment methods. Among other things, treatment of comorbidities (heart, vessels, lungs, kidneys) before, during and after the treatment of cancer has received more focus during this period.
To show mortality from ovarian cancer over time, we use rates instead of the actual number of patients who die. Rates are best suited to show time trends since they take into account that the population of Norway is increasing.
Development over time
The figure shows trends in incidence (red), mortality (pink) and 5-year relative survival (brown) of ovarian cancer in the period 1965-2022. From figure 9.1-R in Cancer in Norway 2022 (Norwegain only).
The incidence of ovarian, fallopian tube and peritoneal cancer Norway has decreased in recent years for women between the ages of 50 and 69. Mortality has fallen over the past 40 years for all age groups.
One can see a general increase in incidence up to the 80s, then one can see a tendency to decline in incidence in the age groups from 30 to 69 years. The prevalence in the age group over 70 years has been relatively stable over the past 30 years. The reasons for the decline in incidence in recent decades have not been established, but contributing factors may be the use of oral contraceptives and increasing use of preventive treatment with removal of the ovaries and fallopian tubes in cases of hereditary predisposition to ovarian cancer.
National Quality Registry for Gynecological Cancer
The National Quality Registry for Gynecological Cancer contains data from 2012 onwards and was granted national status in 2013. Currently, the registry contains extended clinical and pathology data on cancer and borderline tumours (tumours with low malignancy potential) in the ovary, fallopian tube and peritoneum. From 2019, the registry has been expanded to include registration of data on cervical cancer.
The Quality Registry collects data on assessment and treatment of this patient group. The purpose is to use the data from the registry to illustrate practice in hospitals, which can be of help in assessing practice in individual hospitals and for the patient group as a whole.
Read more about the National Registry for Gynecological Cancer
The regional health authorities have organised operations for ovarian cancer so that patients undergo surgery at one of the country's university hospitals with special expertise in gynaecological oncology. These are: Oslo University Hospital (Radiumhospitalet), Haukeland University Hospital, Stavanger University Hospital, St. Olavs Hospital in Trondheim and University Hospital North Norway in Tromsø.
Below we show examples of results from the Gyn Cancer Registry's annual report 2022:
The number of operations for ovarian cancer performed at the country's hospitals. From Figure 3.14 in the annual report.
The European Society of Gynaecological Oncology (ESGO) uses the number of surgeries performed at a hospital as a quality indicator. They define more than 100 operations per year in a hospital as the optimal, more than 50 operations per year are defined as an intermediate target, while they believe that more than 20 operations per year per hospital is a minimum requirement. The robustness requirements of the Norwegian Directorate of Health for Ovarian Cancer recommend a minimum of 20 operations per department per year.
The figure above shows the number of surgeries distributed by hospital for 2021 and 2022. Here it can be seen that the hospitals with specialist expertise perform the bulk of the operations. All hospitals with specialist expertise performed more than 20 operations per year. Only OUS, the Norwegian Radium Hospital, achieves ESGO's optimal goal of more than 100 operations per year.
The figure also shows that some operations are performed in hospitals without specialist expertise (74 operations in 2022). It is known that some patients undergo surgery in local hospitals when emergency operations are needed or in cases of assumed benign disease.
A total of 478 operations were performed in 2022 in Norway. This includes all procedures with a registered clinical surgery report or pathology results, and may include primary surgery, staging/reoperations, diagnostic surgery, operations or palliative surgery. 39 of the operations in 2022 were staging/reoperations. The figure shows that there has been an increase in the number of surgeries from 2021.
Download annual reports for the National Registry of Gynecological Cancer (Norwegian only)
Steps you can take to reduce your risk of getting ovarian cancer
- Be smoke-free
- Avoid coming into contact with asbestos
- Keep a healthy body weight, avoid overweight and obesity
- Birth control pills have protective effect
- Use estrogens after menopause. The risk is lower if you take a combination of oestrogen and progesterone
Source: helsenorge.no
Read more about cancer prevention at kreftregisteret.no - all cancers
Questions about cancer
The Cancer Registry of Norway is a research institution. Our professionals therefore do not answer questions about diagnosis, assessment, treatment and follow-up from patients or their relatives.
Questions about this should be directed to your own GP, treating institution or the Cancer Society Advisory Service tel: 21 49 49 21
Useful Links
Read about ovarian cancer on helsenorge.no
National action programme with guidelines for gynaecological cancer
Ovarian Cancer Facts - kreftforeningen.no
Ovarian, Fallopian Tube, and Primary Peritoneal Cancer on National Cancer Institute website
