The results were found in two studies presented at the 2005 RSNA meeting in Chicago by Dr. Claudia Henschke, professor of radiology at Cornell University's Weill Medical College and director of chest imaging at New York Hospital-Cornell Medical Center in New York City.
Finding multiple lesions
The staging of multiple cancers is an important topic that should be addressed in light of screening rather than symptom-based diagnosis, Henschke said in her presentation.
"What we've found is that when you have CT screening, maybe 15% of the screen-diagnosed cases have more than one cancer, with no evidence of metastases to the lymph nodes or sites outside the lung," she said. "Some of those are only found later on, after the resection has occurred. And the current staging criteria require that these cases be classified as inoperable stage IIIb if they're in the same lobe or stage IV if they're in the other lobe."
The study sought to determine whether such classifications were appropriate in the setting of asymptomatic, latent lung cancers diagnosed as a result of screening.
Henschke, along with colleagues Drs. Sone Shusuke, Steven Markowitz, Karl Klinger, Melvyn Tockman, and Dorith Shaham, identified all resected non-small cell lung cancers without evidence of metastases to the lymph nodes or to sites outside the lung, based on baseline CT screening and follow-up.
A panel of experts reviewed each case following a detailed pathology protocol, and Kaplan-Meier analysis was used to determine the eight-year case fatality rate for the cases with solitary and multiple lung cancers, Henschke said.
Of 291 non-small cell lung cancers without evidence of metastases, 256 or 88% were solitary, and 35 or 12% of the cases were multiple cancers.
"The sizes were unusually similar (between) the solitary lesion and the dominant cancer of the multiple (lesions), 12 mm and 13 mm, respectively," she said. In the 35 cases of multiple cancers, the other lesion was in the same lobe in 12 cases, in another lobe in 18, and in both the same lobe and another lobe in five cases where more than two cancers were found.
The cell types in cases of multiple lesions were the same in nine patients and different in 14. The eight-year fatality rate for solitary cancers was 2.7% (95% CI: 2.7%-2.8%), and 0% for multiple malignancies.
"In other words, we've had 100% survival to date of those who had nonsolitary lung cancers if they were resected, and the solitary (lesions) slightly lower," she said. "Our conclusion is that cases diagnosed as a result of CT screening without metastases to lymph nodes or sites outside the lung but with multiple cancers really had a lower case fatality rate, although not significantly lower, than those with solitary nodules. And that suggests that resection is beneficial in those cases."
For the purposes of long-term follow-up, Henschke suggested that such cases be classified as TNM status indeterminate or perhaps stage I* rather than inoperable.
Fewer metastases; size and lymph node involvement well correlated
Another study presented by Henschke at the RSNA meeting examined data from 27,701 subjects who underwent screening and follow-up under I-ELCAP. In all, 438 cases of lung cancer were found, with each case characterized as to tumor diameter, consistency, and the presence or absence of metastases (N0M0) at diagnosis, regardless of whether it was delayed.
In all, 410 of the 438 cancers were non-small cell carcinomas. The percentages of cases without lymph-node metastases were 91%, 85%, and 61% for tumor size categories less than 15 mm, 16-25 mm, 26-35 mm, and 35+ mm, respectively, the authors wrote in their abstract.
"The gradients in the successive percentages of N0M0 cases were significantly different (p < 0.05, one-sided), except between the last two categories and held for solid nodules but not subsolid ones," the group wrote. "For the 28 small cell carcinomas, the percentage for those 25 mm or less as compared with those greater than 25 mm was 64% and 21%, respectively, (which) was significantly different (p = 0.01, one-sided).
The study confirmed the strong relationship between tumor diameter and lymph node status for non-small cell lung cancers presenting as solid nodules, Henschke's team concluded. In addition, the percentages of N0M0 (nonmetastatic) lesions in screen-diagnosed lung cancers were much higher than previously reported in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry.
"These results confirm the usefulness of finding latent lung cancers at small sizes, and suggest that tumor diameter serves as a prognostic value for curability as well," the group concluded.
By Eric Barnes
AuntMinnie.com staff writer
January 9, 2005
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