Could Patients Older than 75 Years Benefit from a Systematic Breast Cancer Screening Program?

Discussion

Nowadays, life expectancy at 75 years is far from negligible. However, no national BC screening program has ever been set up in any country beyond that age. BC incidence increases with age, including for the elderly, therefore addressing the question of extending prevention guidelines to include that age group seems a priority (6-10).

Before considering extending BC screening to the elderly, disease aggressiveness should be assessed at this age. Hartman et al. have highlighted higher rates of invasive BC after 75 years (22 out of 26 studied cases) in comparison to average reported proportions in the 50-74-year-old patient cohorts (11). Our cohort also presented high rates of invasive disease, but proportions were even greater when diagnosis was established following CM. Our findings corroborate those of Field et al. and show that contrary to what is sometimes reported, BC at an older age is not a slow-evolving, almost chronic, disease but at least as aggressive cancer as when diagnosed in younger patients (12, 13). Progression of BC is another fundamental parameter when contemplating screening. Evidence suggests successive steps, from a pre-cancerous stage to a pre-invasive and ultimately, a true invasive disease (14, 15). The finding that in our cohort, the SM group presented lower degrees of infiltration (compared to the CM group) suggests that when diagnosis occurred at an earlier stage of the cancer's progression could allow for a precocious management. It is, nevertheless, important to note that prognosis is also conditioned by other factors, notably immunohistochemical cancer profile, which, in patients older than 75 years, may define a less aggressive disease (positivity for oestrogen/progesterone receptors, low proliferative rate, absence of p53 accumulation, bcl-2 overexpression, diploid DNA content) (16, 17).

• Download figure
• Open in new tab
• Download powerpoint

Figure 1.

Kaplan–Meier plots of (A) overall and (B) disease-free survivals. In both plots, upper curves indicate systematic mammography (N=57), while lower curves indicate clinical manifestations (N=283). p-Values were calculated using the log-rank test.

A successful BC prevention program is defined by its capacity to detect disease at its earlier stages. Regarding older patients, it was showed that early-stage BC is detected less frequently compared to younger women, essentially due to lack of screening (18). In their work, Molino et al. have shown a rate of T1 tumors at diagnosis of 70% for BC patients between 45 and 64 years of age and of only 47% after 75 years (19). In our cohort, these numbers were higher in the screened group, as 61.4% of BC were T1 tumors (versus 14.8% in the CM group), thus suggesting an earlier diagnosis when a SM was performed. Consequences were also observed in terms of management, as patients with earlier BC stages in the SM group benefited more often from surgery, which implied a curative perspective. Certain authors argue that surgery is not a reasonable option in older patients, but global BC operative mortality in this population, remains low, estimated at 1-2% (8). This seems to be an acceptable risk if a curative perspective is contemplated, though indications should be modulated after a comprehensive assessment of associated comorbidities. Furthermore, earlier detection in our SM group appeared to enable higher proportions of conservative management, as 74.5% of our surgically treated screened population had neither mastectomy nor AD. Minimally invasive techniques are especially attractive in this age group, as they allow shorter hospitalizations and faster rehabilitations, which are correlated to lower rates of autonomy loss and overall less morbidity (20, 21). Invasive surgery is not the only type of cancer management associated with high morbidity rates. Chemotherapy also has a significant impact, particularly in older patients who usually present lower tolerance levels to the many listed side-effects (22). Our data showed no metastatic BC in the patient group who had benefited from SM, with a statistically significant difference compared to women presenting CM. These important findings are signifying a lower specific mortality for the screened women, a lesser need for chemotherapy and therefore, a lower treatment-induced morbidity.

Studies investigating mortality in older patients with BC are scarce. Our data showed that overall and specific mortalities were higher when diagnosis was the result of CM.The same conclusions were made by Barco et al. who also viewed mass screening as an improvement for women older than 69 years (23). Furthermore, differences of overall and disease-free survivals were both statistically as well as clinically significant. Indeed, estimated at 14.2 and 18.4 months respectively in our series, this represents a noticeable gain in terms of life expectancy in the SM group, especially for older patients.

Methodological limits stem from retrospective analyses and ours should be mentioned, as well. Indeed, the aim of our study was to obtain a comprehensive record of all treated BC in our oncologic referral center. Thus, patients in the two groups were not paired for comorbidities. This could represent a bias as it can be anticipated that patients receiving regular mammographies may also benefit from closer medical monitoring and are, thereby, more likely to receive better care for their potential associated diseases. This confounding factor should nonetheless be put into perspective, as in organized mass screenings the less observant patients are also the most isolated in terms of medical coverage (24).

In conclusion, our results constitute a strong argument for reconsidering age limits of national BC screening programs as this could imply important benefits for older patients in terms of reduction of mortality and treatment-induced morbidity.