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A. Jirapatnakul
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P3.06 - Poster Session/ Screening and Early Detection (ID 220)
- Event: WCLC 2015
- Type: Poster
- Track: Screening and Early Detection
- Presentations: 2
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.06-006 - Extent of Progression for Small Cancers in a Screening Program Even with Proper Follow-Up (ID 3096)
09:30 - 09:30 | Author(s): A. Jirapatnakul
- Abstract
Background:
Current guidelines for repeat CT imaging of small nodules detected during screening are a function of the size and consistency of the nodules and the round it was detected. They attempt to balance the frequency with which a change would genuinely occur (i.e. the frequency with which a nodule of a given size is a cancer) with the ability to actually measure the change should it have occurred. Recently the American College of Radiology has established a new set of guidelines for this purpose called LungRads. This study analyzes the change in nodule volumes and doubling times for small nodules if the LungRads guidelines are followed.
Methods:
The LungRads protocol focuses on providing categories for nodules based on their degree of suspiciousness and provides suggestions for follow-up. They also provide criteria so as to determine when growth is genuine —that is, the change in size is beyond what could have occurred solely as a result of measurement error. Genuine growth defined as increase in diameter of >1.5 mm. For purposes of estimating change in nodule volume and doubling times associated with them, we used the time intervals in LungRads for follow-up and derived the doubling times necessary for a nodule to reach the definitional growth threshold. We assumed a spherical model for the nodules and used a simple exponential growth rate. We focused on solid nodules where the range of growth rates is known to be large and they are most accurately measured.
Results:
For LungRads Category 2, where 6 month follow up CT is recommended, in order for a 4 mm nodule to grow sufficiently so as to pass the size threshold where change could be detected, it would need to have a doubling time faster than 129 days, anything slower would not achieve the necessary size change and it would only then be rescanned 6 months later at an annual repeat scan and it would then potentially reach a size of 8.0 mm. For category 4A, LungRads recommends repeat scanning in 3 months. According to the protocol, a 6 mm nodule would need a doubling time of 92 days for detection otherwise at one year it will reach a size of 15.1 mm.
Conclusion:
The change threshold for growth and time intervals between scans can have serious consequences downstream in terms of how large a tumor might become before it can reliably be diagnosed. The ability to better define the threshold for when change has occurred will always be beneficial as it will allow not only the very fast growing tumors to be diagnosed but those with more typical doubling times as well. The LungRads protocol keeps the smallest size category of tumors from growing beyond 15 mm when workup is initiated.
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P3.06-019 - Lung Cancer Deaths in the NLST Attributed to Nonsolid Nodules (ID 3022)
09:30 - 09:30 | Author(s): A. Jirapatnakul
- Abstract
Background:
There has been increasing awareness of the more indolent course of cancers manifesting in nonsolid nodules, especially among those where the nodule is solitary or dominant. There have been reports of virtually 100% cure rates upon resection and most recently, the recommendation from the ACR in their Lung-RADS screening guidelines is for those nonsolid nodules less than 2 centimeters to be followed by annual screening without additional evaluation. In order to further evaluate the aggressiveness of these types of cancers in the screening setting, we determined how frequently they were the cause of death (COD) within the NLST.
Methods:
We searched the NLST database to identify all participants who had a diagnosis of lung cancer after a positive result on CT screening and whose death was attributed to lung cancer by the NLST endpoint verification process. Among them, 28 participants had at least one nonsolid nodule identified on CT in a screening round. Among these, all cases where the nonsolid nodule could not identified in the study year the cancer was first identified (cancyr) or in the location of the confirmed lung cancer were excluded. All images associated with the remaining 8 cases were downloaded from The Cancer Imaging Archive (TCIA) using the NLST Query Tool and reviewed by three radiologists (DY, DX, MH) to assess nodule consistency and location.
Results:
Among the 8 cases reviewed by the radiologists, only 5 cases had at least one nonsolid nodule. The remaining three cases had no CT evidence of a non-solid nodule (Table 1). Among the 5 cases with nonsolid nodules, 2 cases had another large solid nodule (average diameter of 54.5mm and 15 mm) in the same lobe which was the probable lung cancer that was the cause of death. In another case, the nodule was less than 5 mm in diameter and stable for 3 years, and in another the cause of death was small cell carcinoma which is not known to manifest as a nonsolid cancer. One case manifested on baseline scan with multiple nonsolid and part-solid nodules which all grew on successive annual scans. Table 1. Lung cancer deaths with non-solid nodules in NLST database
*ns-nonsolid; ps-part-solidCase Any NS nodules Size of largest NS Multiple/solitary Stage/Cell-type Comments 128534 Y 29 x 19 Solitary NS Solitary solid IIIA/Squamous cell Large solid nodule (57 x 52) 134088 Y 27 x 20 Multiple NS Multiple solid IV/Small-cell 212718 Y 26 x 26 Multiple NS Multiple PS IV/BAC Cancer reported in all lobes 116279 Y 5 x 4 Solitary NS IV/Carcinoma NOS NS nodule appears stable over 3 years 126576 Y Multiple NS Solitary solid IA/Adeno-mixed Growing solid nodule, 15 mm 117025 N Multiple solid IV/Adeno NOS 208792 N Solitary solid IIIA/Squamous cell 218307 N Solitary solid IIIA/Squamous cell
Conclusion:
It seems unlikely that within the NLST, there were cases of lung cancer specific death that were attributable to cancers manifesting as a solitary or dominant nonsolid nodule. This lends further support that lung cancers manifesting as nonsolid nodules have an indolent course.
