Washington, August 19 (ANI): A study conducted at Washington University School of Medicine in St. Louis and collaborating institutions suggests that when oestrogen-lowering drugs no longer control metastatic breast cancer, the opposite strategy may work.
During the study, increasing oestrogen levels was found to benefit 30 percent of women whose metastatic breast cancer no longer responded to standard anti-oestrogen treatment.
Not only did oestrogen treatment often stop disease progression, in some patients metastatic tumours became resensitised and again responded to anti-oestrogen treatments.
"The women in the study had all experienced a relapse while on estrogen-lowering drugs, and their disease was progressing. So they were faced with undergoing chemotherapy. We found that estrogen treatment stopped disease progression in many patients and was much better tolerated than chemotherapy would have been," says lead author Dr. Matthew J. Ellis, an oncologist with the Siteman Cancer Center at Washington University and Barnes-Jewish Hospital.
The study involved 66 postmenopausal women with breast cancer that had spread beyond the breast. All participants were originally diagnosed with oestrogen receptor positive (ER ) breast tumours, meaning oestrogen stimulated tumour growth.
Seventy-five percent of breast cancer cases are ER. All participants had received aromatase inhibitor treatment, which severely lowers oestrogen levels, but their metastatic tumours had later reappeared or resumed growing.
The research team compared a high 30-milligram daily dose of oestrogen to a low 6-milligram daily dose, and evaluated how well the treatments controlled the women's metastatic cancers, and how the treatments affected their quality of life.
Ellis said that 30 per cent of the participants were found to experience a clinical benefit-their tumours either shrank or stopped growing.
Interestingly, the researchers could even predict fairly accurately which patients would have the positive response.
Conducting standard positron emission tomography (PET) scans before oestrogen treatment and 24 hours later, they observed that metastatic tumors that glowed more brightly after oestrogen was started were much more likely to be affected by oestrogen therapy.
In 80 percent of women with PET flare reactions, tumours responded to oestrogen therapy, and in 87 percent of women without PET flares, tumours did not respond to oestrogen.
Questionnaires filled out by the participants showed that adverse reactions to oestrogen during the study included headaches, bloating, breast tenderness, fluid retention, nausea, and vomiting. Patients receiving the high oestrogen dose had more severe side effects.
"The older women in the study were, the fewer estrogen-related symptoms they had. But overall, we demonstrated clearly that the low dose was better tolerated than the high dose and was just as effective for controlling metastatic disease," says Ellis also professor of medicine in the Division of Oncology.
In the 30 percent of participants who responded to oestrogen, tumours often began to grow again after a period of months or years. But in a third of the recurring cases, the researchers showed that the women's tumours had become resensitised to anti-oestrogen therapy.
The tumours shrank or stopped growing when the patients went back on their original aromatase inhibitor treatment.
The study has been reported in the Journal of the American Medical Association. (ANI)