Nonsolid lung nodules, no matter the size, can be safely monitored with yearly CT screening, according to a newly published study that found any lung cancers diagnosed among these nodules to be slow growing and treatable even after a conservative screening strategy.

The findings, published online in Radiology, could help manage nonsolid nodules that have presented a challenge for physicians wary of overdiagnosis.

“This is a major step forward for lung cancer screening protocols,” said lead author David F. Yankelevitz, MD, from Mount Sinai School of Medicine in New York City, in a statement. “It will help us cut down on the number of surgeries and unnecessary imaging tests.”

Assessment of nonsolid nodules using morphologic appearance and growth is difficult, as the nodules tend to be irregular with ill-defined margins, explained the authors. Fine-needle aspiration is operator and cytologist dependent.

With this in mind, Yankelevitz and colleagues analyzed results from 57,496 participants in the International Early Lung Cancer Program (I-ELCAP) who had undergone baseline and annual repeat screenings from Jan. 1, 2001, to Dec. 31, 2013. They were looking to track the prevalence of nonsolid nodules and their effect on long-term outcomes.

Among the participants, a nonsolid nodule was identified in 2,392 baseline screenings (4.2 percent), with pathological analysis leading to the diagnosis of 73 cases of adenocarcinoma in this group of nodules. Additionally, 485 new nonsolid nodules were identified in the nearly 65,000 annual repeat screenings included in the study, for a rate of 0.7 percent. Of these newly identified nodules, 11 had a diagnosis of stage I adenocarcinoma, but none were in nodules 15 mm or larger in diameter.

Nonsolid nodules became part-solid in 22 cases, with a median transition time of about two years from initial identification of the nonsolid nodule to the emergence of the solid component.

Surgical treatment, consisting of lobectomy, sublobar resection or bilobectomy, was 100 percent curative with a median time to treatment of 19 months.

“The implication of the long-term survival of 100 percent, regardless of the cancer size or time to treatment, is that there is no added benefit to earlier invasive diagnostics and treatment of these cancers,” wrote the authors.

“The absence of interim, symptom-prompted diagnoses and absence of cancers manifesting as nonsolid nodules larger than 15 mm in annual repeat rounds provide further support of the indolent nature of these cancers,” they added.

As CT screening becomes more prevalent and early stage lung cancers are more frequently seen, Yankelevitz and colleagues stressed the need for identifying the most appropriate management strategies. They noted that these results could help in shared decision-making process between patients and physicians.