Breast cancer may come back even after 24 years

21 Jan 2016

Patients with ER-positive (ER+) breast cancer had a significant risk of relapse even after more than 10 years of follow-up, analysis of data from the International Breast Cancer Study Group clinical trials (IBCSG) indicated.

Annualized hazards of recurrence remained elevated beyond 10 years, even for those with no axillary involvement and for those with one to three positive nodes, according to Marco Colleoni, MD, of the European Institute of Oncology, Milan, Italy, and colleagues.

Clinical results from more than 4,000 patients

The analysis looked at data from 4,105 eligible patients with breast cancer who entered the five prospective, randomized IBCSG clinical trials I to V from 1978 to 1985. Annualized hazards were estimated for breast cancer-free interval, which was the primary end point, as well as for disease-free survival and overall survival.

The analysis of the results revealed that:

The annualized hazard of recurrence in the first 5 years for all patients was 10.4% with a peak of 15.2% between years one and two
Patients with ER+ disease had a lower annualized hazard compared with those with ER-negative disease during this time
After 5 years, however, a very different pattern emerged. In years five to 10, patients with ER+ disease had a hazard of 5.4% compared with 3.3% for patients with ER-negative disease. Similarly, hazards were higher for patients with ER+ disease versus those with ER-negative disease at 10 to 15 years: 2.9% versus 1.3%; 15 to 20 years: 2.8% versus 1.2%; and 20 to 25 years: 1.3% versus 1.4%.

The investigators noted that in the ensuing decades, breast cancer relapse-free survival has improved, and that this is probably related to modern adjuvant treatment.

“Newer and most effective treatments are now available”

The regimens used in the IBCSG studies have been replaced by newer and more efficacious chemotherapy regimens and longer-duration adjuvant tamoxifen or aromatase inhibitors, commented Kathleen I. Pritchard, MD, of Sunnybrook Odette Cancer Centre and the University of Toronto, Ontario, Canada. "There may be ongoing risk out to 24 years or perhaps even longer for those patients who have ER+ breast cancer. This risk is reduced by endocrine adjuvant therapy such as tamoxifen or aromatase inhibitors which are now being given for 5 or 10 years and for some, perhaps longer. More data is emerging as to how long this should be."

Pritchard and co-authors Jonas Bergh, MD, PhD, and David Cameron, MD, PhD, noted that ovarian ablation is still a valid adjuvant therapy option for patients with premenopausal ER+ breast cancer. Nevertheless, they added, "in some instances, the best available chemotherapy regimens followed by the best available endocrine therapy options should be recommended for higher-risk and/or younger patients."

The role of postoperative radiotherapy

The editorialists also pointed out that none of the patients in the IBCSG studies were offered postoperative radiotherapy, as per clinical management at that time. Also, the radiotherapy used in the five IBCSG studies was different from what is used now.

While it is still correct not to offer postoperative radiotherapy for patients with axillary lymph node-negative disease who are undergoing mastectomy, this is not the case for women with axillary node-positive disease, said Pritchard and colleagues. "Postoperative loco-regional radiotherapy reduces the risk of loco-regional recurrence by 2/3, translating into an 8% gain in breast cancer mortality at 20 years but only a 5% overall survival gain, at the expense of serious cardiovascular morbidity and mortality," they said.

Calling for long-term treatment evaluation

"The risk of breast cancer recurrence continues through 24 years after primary treatment, supporting the importance of continuing care for patients with breast cancer," the investigators reported. "New targeted treatments and different modes of breast cancer surveillance for preventing late recurrences within this population should be studied. Developing cost-effective mechanisms to maintain the follow-up of patients enrolled in current randomized clinical trials is essential."

They called on decision-makers in cancer care -- insurance companies, governments, and regional healthcare funders -- to make long-term evaluation of cancer treatment possible.

Source: MedPage Today

Breast cancer may come back even after 24 years