Breast Cancer Followed by Ovarian Cancer?

Summarized by Robert W. Griffith, MD
October 7, 2002 (Reviewed: October 19, 2004)

Introduction

Women with breast cancer have a slightly increased risk of developing ovarian cancer. This risk is greater in women under 50 at the time they are diagnosed with breast cancer. And the risk is much greater in breast-cancer patients with abnormal BRCA1 or BRCA2 genes. However, screening for gene mutations is often difficult to have done in some places, and it can be quite expensive. Swedish scientists have studied whether collecting information from a breast-cancer patient about her relatives' medical history would be able to predict an increased risk of her developing ovarian cancer.

The study design

In Sweden, national registries keep track of the occurrence of cancer and family relationships, with a high degree of accuracy. The scientists were able to identify over 30,000 breast-cancer patients born after 1931 who had information on the occurrence - or not - of breast cancer and ovarian cancer in first-degree female relatives (i.e. mothers, sisters, daughters). They found almost 150,000 relatives who met these requirements.

The increased risk of ovarian cancer was calculated for three different age groups and for different family histories of cancer. The actual risk of a breast-cancer patient getting ovarian cancer over a 30 year-period was also calculated.

What was found

The average age of the women when breast cancer was diagnosed was 48. For the entire group of over 30,000 women, the likelihood of developing ovarian cancer was doubled in those who had a first-degree relative with breast or ovarian cancer.

Breaking down the results according to age, it was found that the risk was much higher in women under 40 at the time of their diagnosis of breast cancer. Overall, breast-cancer patients without a family history of either tumor had a 60% increased likelihood of developing ovarian cancer, but if they were under 40 the risk was three times (300%) greater.

For patients diagnosed with breast cancer before they were 40, a family history of breast cancer meant a 5.6-times increase in the risk of ovarian cancer, and with a family history of ovarian cancer, the risk was 17-times as great. In breast-cancer patients over 40 at diagnosis the likelihood of ovarian cancer was smaller, but was still increased if a relative had one of these tumors.

What's the value of this information?

This study confirms that women with breast cancer, in particular those diagnosed at a young age and with a history of breast or ovarian cancer in first-degree relatives, are at an increased risk of ovarian cancer. It's real value lies in its demonstration of the use of the medical history of close relatives in deciding the best course of action in some health matters. Gene mutation testing is an expensive procedure, and it's not always readily available.

For young women with breast cancer, a careful family history can provide the necessary information to justify appropriate screening, counseling, and perhaps even removal of the ovaries in women at greatly increased risk.

Source

• Bergfeldt K, Rydh B, Granath F, et al. Risk of ovarian cancer in breast-cancer patients with a family history of breast or ovarian cancer: a population-based cohort study. Lancet (Online) 2002, accessed 9/18/02: http://image.thelancet.com/extras/01art1109web.pdf

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