A new study provides improved insights into the incidence and survival rates of osteosarcoma since 1975, with evidence pointing to a relatively recent improvement in survival among patients with metastatic disease but increased incidence in males aged up to 24 years.

The findings of the study are being presented by Trevor Gulbrandsen, MD, an orthopaedic surgery resident from the University of Iowa Hospitals and Clinics in Iowa City.

In their study, Dr. Gulbrandsen and colleagues explained that osteosarcoma is the third most common cancer in adolescents and the most prevalent primary malignancy of bone. Although osteosarcoma predominantly occurs in adolescents, the second incidence peak is observed in individuals older than 60 years.

Due to the introduction of chemotherapy several decades ago, overall survival has improved considerably. According to the investigators, previous research shows that rates of osteosarcoma-related survival have remained relatively stable since at least the 1990s. Despite this apparent plateau in survival, the researchers noted there is currently a lack of robust reports for incidence and survival of the disease over the past 15 years.

To address this research gap, Dr. Gulbrandsen and colleagues examined the National Cancer Institute’s population-based Surveillance, Epidemiology, and End Results (SEER) program to identify case and survival rates of osteosarcoma between 1975 and 2018. In total, the investigators identified 5,551 patients from the SEER database who were diagnosed with osteosarcoma during that defined study period.

Researchers collected and assessed data on disease incidence, patient characteristics, and survival rates in the database population. They also performed subanalyses based on age, year of diagnosis, sex, and stage.

From 2015 to 2018, the overall age-adjusted annual incidence of osteosarcoma was 3.3 cases per 1 million people. Between 1975 and 2018, the researchers found that the incidence of osteosarcoma followed a bimodal distribution, with a first peak at ages 15 to 19 years (8.2 cases/million) followed by a second peak at ages 75 to 79 years (4.6 cases/million). A higher incidence of secondary osteosarcoma and Paget disease was associated with the second incidence peak.

From 1990 through 2018, the overall incidence of osteosarcoma fell from 3.1 to 2.7 cases per 1 million people. Yet, the annual incidence since 1975 has increased in the youngest patient subgroup (ages 0–24): 3.7 cases per 1 million people in 1975 to 1979 to 5.2 cases per 1 million people in 2015 to 2018, for an annual percent change of 0.6 (P <0.05; fig. 1).>

Survival from osteosarcoma markedly improved between the periods of 1975 to 1989 and 1990 to 1999, yet the researchers wrote that there has been minimal change in five-year survival for the disease since the 1990s. For instance, the five-year relative survival for all osteosarcoma cases was:

• 48.1 percent from 1975 to 1989
• 61.5 percent from 1990 to 1999
• 62.2 percent from 2000 to 2009
• 60.7 percent from 2010 to 2017

Although survival improved across all age groups between 1975 and 1989, no significant change in five-year survival was observed between 1990 to 1999 and 2010 to 2017 in patients aged 0 to 24 years (P = 0.20), 25 to 64 years (P = 0.97), or 65 years and older (P = 0.27).

The five-year survival rate in patients with local/regional disease significantly improved between 1975 to 1989 and 2010 to 2017 (55.8 percent versus 70.5 percent, respectively; P <0.01). survival also significantly improved in distant disease between those time periods (12.2 percent versus 28.1 percent;>P <0.01). in addition, the five-year survival rate for patients with distant disease trended toward improvement between 1990 to 1999 and 2010 to 2017, but the difference between those periods was not statistically significant (22.4 percent versus 28.1 percent;>P = 0.33).

In patients with metastatic osteosarcoma, the five-year survival rate improved in patients aged 0 to 24 years from 1975 to 1989 (11.0 percent) and 1990 to 1999 (34.1 percent), yet little change has occurred since, with a 36.2 percent survival rate in 2010 to 2017.

The authors observed an increase in survival since 1990 in patients aged 25 to 64 years with distant metastases, from 7.8 percent in 1990 to 1999 to 11.3 percent in 2000 to 2009 to 21.6 percent in 2010 to 2017. However, the difference between 1990 to 1999 and 2010 to 2017 was not statistically significant (P = 0.19).

The five-year survival rate has remained near 0 percent since 1975 in patients aged 65 years and older with metastatic disease. However, two-year survival in those patients has improved over time: 4.3 percent from 1975 to 1989, 10.7 percent from 1990 to 1999, 9.6 percent from 2000 to 2009, and 14.6 percent from 2010 to 2017.

The researchers concluded that additional studies are needed to elucidate the reasons why some patients have experienced a survival benefit in recent years.

The study will be on display as Poster P0685 on Friday in Academy Hall, from 7 a.m. to 5 p.m.

Dr. Gulbrandsen’s coauthors of “An Osteosarcoma National Update: 40 Years of Incidence and Survival Trends” are Christopher Robert Halbur, BS, and Benjamin James Miller, MD, MS, FAAOS.

Brandon May is a freelance writer for AAOS Now.