Secondary primary malignancies worsen multiple myeloma survival

While survival among multiple myeloma (MM) patients has been improving over time, the development of secondary primary malignancies (SPMs) seems to offset this effect by increasing the risk of mortality, a recent study has found.

Drawing from the Netherlands Cancer Registry, the researchers assessed 18,030 adult MM patients, of whom 8.3 percent (n=1,489) had a prior malignancy diagnosis (PMD) while 7.4 percent (n=1,334) developed an SPM. Benign and in situ tumours were excluded, as were basal cell carcinomas and patients who were diagnosed with MM at autopsy.

Multivariable competing-risk regression analysis found no significant link between PMD and SPM (subdistribution hazard ratio [SHR], 0.97, 95 percent confidence interval [CI], 0.79–1.18; p=0.73). The same remained true when PMDs were treated with systemic or radiotherapy (SHR, 0.94, 95 percent CI, 0.69–1.28; p=0.70) or were not treated (SHR, 0.98, 95 percent CI, 0.76–1.27; p=0.89).

In contrast, age was a significant correlate of SPMs. Compared to patients aged 18–65 years, the risk of SPM was significantly elevated in those aged 66–70 years (SHR, 1.19, 95 percent CI, 1.01–1.40; p=0.04), but significantly suppressed in those aged >70 years (SHR, 0.84, 95 percent CI, 0.75–0.95; p<0.01). Such a pattern suggests that beyond a certain age, patients are more likely to die first before developing an SPM.

Of note, patients who had had a PMD, whether or not it was treated via systemic or radiotherapy, saw higher mortality risk than patients without a PMD. Similarly, the development of SPM aggravated death risk independently of other potential correlates.