Introduction

Breast cancer is the commonest cancer in women, and is second only to lung cancer as the most lethal. Two-thirds of newly diagnosed cases are in postmenopausal women (defined as over 55 years of age), with the peak incidence in the group aged 75 to 79. The mortality rate from the disease also increases with age, with the highest rate in those 85 and older. In parallel with these increases, health problems are more common with advancing age. Does age-related comorbidity affect the treatment decisions and the outcome in postmenopausal breast cancer? A new study done by the US National Institutes of Health (NIH) has examined this question.

Method

Six US National Cancer Institute registries were used to obtain data on tumor staging, primary treatment given, and the comorbid diseases affecting the patient at the time of initial cancer diagnosis. Follow up information was limited to 30 months after diagnosis.

Patients were grouped by age at diagnosis - 55-64 years, 65-74 years, and 75 years and above. Tumor staging was done using the American Joint Committee on Cancer classification system. Comorbidities were classified as either being a current management problem, or not a current problem.

Results

The collective included 1,800 patients aged 55 to 101 years (93% white, 5% black, 2% other races). 73% were diagnosed as having stage I or II breast cancer, 10% with stage III or IV, and 17% (300 patients) had no stage assignment. The absence of staging was associated with increasing age - the proportion reached over 50% in women over 85. Inability to stage was because of lack of data on nodal, primary and/or metastatic tumor status.

Of the women with stage I and II breast cancer, 95% received treatment in agreement with the 1990 NIH Consensus Statement (i.e. partial mastectomy and radiation, or modified radical mastectomy). Patients in older age groups were less likely to receive therapy consistent with the guidelines; among those receiving partial mastectomies, older patients received radiation therapy less frequently. Women aged 70 years or above were significantly less likely to receive axillary lymph node dissection.

Not surprisingly, comorbidities increased with age. In the total collective 92% of the women had at least one comorbidity; the commonest was hypertension, followed by arthritis. Using a statistical model that adjusted for age and tumor stage, it was found that diabetes, renal failure, stroke, liver disease, previous malignancy, and smoking were predictors of early mortality.

Of the 263 deaths that occurred during the 30-month follow-up period (15% of the collective), over half (51%) were due to breast cancer. This proportion decreased in the older age groups (75 years and above), heart and cerebrovascular diseases being increasingly important causes.

Comment

This study, which used a large, well-documented, highly representative sample, has confirmed what many would have suspected - comorbidity in older patients with breast cancer limits the ability to obtain good staging information, reduces the treatment options in some cases (i.e. radiation after partial mastectomy), and increases the risk of death from other causes than breast cancer. So what are the implications?

The good news is that 95% of the women were given appropriate treatment. However, reliable information on women over 70 with breast cancer is sparse. Increased participation of such women in randomized clinical trials of the efficacy and tolerance of adjuvant therapy is urgently needed. This is necessary to determine if the 15% mortality within 30 months of diagnosis can be reduced, without a concomitant increase in morbidity from side effects. Improved treatment of comorbidities will also offer hope of reducing this mortality rate, so the outlook for older breast cancer patients may be brightening.