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Survival Benefit of New Treatments

It is generally believed that, as new treatments have been introduced for MBC, the duration
of survival in the MBC population has increased. A number of studies have examined this
hypothesis, with data from 1975 through 2008. Some studies have involved de novo cases from
SEER and other registries; others, hospital-based populations with available recurrence and
outcome data. Typically, the studies have examined successive periods over a number of years
to see whether duration of survival has improved over time (see Table 8).

Dawood et al. examined survival among more than 15,000 patients with de novo MBC in the
SEER registries from 1988 to 2003 [103] . They found modestly improved median survival over
time (from 20 months to 27 months) among non-Hispanic white women, but not in black
women, whose median survival remained constant at 17 months. SEER data for many types of
Over the past few cancer have revealed disparities between non-Hispanic white and black populations.
decades, the duration
of survival after a Chia et al. examined data for 2150 MBC patients referred to the British Columbia Cancer
diagnosis of MBC has Agency from 1991 through 2001, a decade during which 7 new MBC treatments became
increased modestly— available in Canada [104] . At the earliest time point, median survival was only 14 months, but it
by months, not years. increased to 22 months by the end of the decade.

Giordano et al. [105] analyzed data from the MD Anderson Cancer Center database for patients
with recurrent breast cancer from 1974 to 2000. The median survival was 15 months for the
earliest cohort to 58 months for the most recent cohort. However, the sample included women
with locally advanced recurrence, which has a better prognosis than distant metastatic disease.
Ruiterkamp et al. studied 8000 patients with de novo MBC in the Netherlands Cancer Registry
diagnosed between 1995 and 2008, finding an improvement in median survival from 17 to 23
months, with the largest increase occurring among patients under 50 years of age [106] . An earlier
(2007) population-based study in northern Holland by Ernst et al. [107] found similar results: an
increase in median survival from 18 months in 1975 to 21 months in 2002.

Finally, Andre et al. [108] analyzed 724 consecutively enrolled patients with de novo MBC, from
3 French cancer centers, diagnosed between 1987 and 2000. Overall, the median survival
improved over time from 23 to 29 months. Among patients with ER+ MBC, median survival
improved from 28 months to 45 months, whereas patients with hormone-insensitive MBC
(TNBC or ER− MBC), median survival was unchanged.

The apparent lack of a survival benefit seen in the Andre et al. study with the use of new
cytotoxic chemotherapy agents in TN or ER− MBC was confirmed by Pal et al., who analyzed
274 patients with de novo MBC patients in the City of Hope, California, registry between 1985
and 2004, to ascertain the possible contribution of newer chemotherapy agents [109] . The
authors concluded that, although overall survival had improved slightly over 20 years, “the
contribution of conventional cytotoxic agents to this improvement is minimal.”

Overall, these studies suggest that improvements in survival duration are due to targeted
treatments for hormonally sensitive and HER2+ breast cancers. Of note, the survival estimates
in these studies could reflect not only evolution of available care but also changes in imaging,
earlier detection of metastatic disease, and changes in the definition of distant metastases.
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