Clue to Cancer Cluster

by Helen Lobato

The statistical findings from the third progress report into the breast cancer cluster at the ABC in Toowong revealed that the risk of breast cancer occurring in the women employees was six times higher than that in the general population of women in Queensland. These findings concluded the five month long study which was conducted on ten female employees at the ABC studios who had been diagnosed with breast cancer over the past 11 years. Eight of the women worked in the newsroom and most had been there for more than five years.

The report concluded that it was highly unlikely that this increase in breast cancer amongst the women was caused by exposure to radio frequency or extremely low frequency electromagnetic radiation. Neither was there found evidence of chemical contamination at the site.

It is worth noting that if purely environmental factors such as chemical contamination or radiation leakage were found to be causative factors then surely we would have seen a rise in cancer amongst men employees at the ABC studio as well as in women. But this was not the case. The cluster concerned 10 women who have developed breast cancer. We have not been informed of any cancer clusters among the men at ABC Toowong. Therefore it appears that there are factors specific to women only that have caused this cancer cluster.

In looking for causation for this cancer cluster we need to extend our definition of environmental causes and look at lifestyle factors among the women such as the practice of smoking, variations in diet, level of alcohol use, and medication usage. The report into the breast cancer cluster at the ABC Toowong did in fact include the relevant lifestyle factors for the women affected by breast cancer.

The ten women were asked questions regarding family history of breast cancer. Their own body weight and height were taken into consideration along with their use of alcohol and smoking history. The level of physical activity was also brought into the investigation along with each woman’s reproductive history.

Interestingly all ten women had used oral contraceptives for periods varying from 2 to 18 years, average 9.4 years. Three of the women had not borne a child and the average number of babies for women was 1.6. Each of the women who had borne a child had breast fed for an average of 2.3 to 12 months and of the ten women, six had a university degree or a diploma. Such factors are very important but were not given the light of day when this story hit the headlines.

One in eight women in Australia will be diagnosed with breast cancer before the age of 85. The number of women diagnosed with breast cancer in Australia increased from 5,318 in 1983 to 12,027 in 2002. It is projected that there will be 13,261 women diagnosed with breast cancer in 2006 and 14,818 in 2011.

The incidence of breast cancer has skyrocketed over the last couple of decades. During this time the lives of women have changed dramatically with fewer babies being born and to older mothers than ever before. Medical researchers have long recognised early puberty, late menopause, small number or no children and lack of breastfeeding as risk factors for the development of breast cancer. Enabling these lifestyle changes was the development of the oral contraceptive pill. The question that needs to be asked is whether the taking of the oral contraceptive pill has any part to play in the development of breast cancer. As reported by the study into the breast cancer cluster all ten women had taken the pill for varying periods of 2 to 18 years.

The Women’s Health Initiative Clinical Trial reported that prolonged exposure to exogenous ostrogens and progestins in hormone replacement therapy increases a woman’s risk of developing breast cancer, and recently the World Health Organisation classified both hormone replacement therapy and oral contraceptives as group 1 carcinogens. A new analysis reveals that U.S. breast cancer rates plunged more than 7 percent in 2003 and strongly suggests that the reason is less hormone use. Millions of women quit taking menopause hormones after a big federal study found that the pills raised the risk of breast cancer.

The estrogen in birth control pills is a synthetic form called ethinyl estradiol. It’s a potent form of estrogen that is roughly four to ten times stronger than that used in different types of HRT.

A meta-analysis 2006 from the Mayo Clinic into oral contraceptive use as a risk factor for premenopausal breast cancer concluded that use of oral contraceptives is associated with an increased risk of premenopausal breast cancer, especially with use before first full term pregnancy. This being due to the fact that the nulliparous breast is made up of undifferentiated structures which are susceptible to carcinogens and it is not until a full term pregnancy that the breast is completely developed and not as vulnerable.

It is known that some cancer clusters exist because people with certain risk factors tend to cluster, some because of environmental factors, especially in occupational settings, and many because of statistical chance. Amongst the 10 women diagnosed with breast cancer at ABC Toowong, six of the women had a university degree or a diploma. Increased rates of breast cancer are present in women in white collar jobs which is related to socioeconomic status and late childbearing. The report also made mention that there were high levels of breast screening amongst the ABC Toowong women perhaps an indication that the women were similar in their status and lifestyle factors.

The ABC building in the Brisbane suburb of Toowong has now been vacated and the cause of a high incidence of breast cancer cases among women staff members is still not clear. As breast cancer rates continue to skyrocket, all possible reasons need to be considered.

Read full report here