Abstract 1899P
Background
There have been wide variations in the reported prevalence (up to 30%) of autoimmune disorders (AID) in TET patients (pts) in small single-center series. RYTHMIC (Réseau tumeurs THYMiques et Cancer) is a French network mandated to systematically discuss every case of TET. A histopathology central review of the samples is performed within a National Histopathological Tumor Board (NHTB). We aimed to assess the prevalence of AID in a large cohort after pathological central review.
Methods
RYTHMIC database, hosted by IFCT (French Intergroup of Thoracic Cancerology), prospectively includes all consecutive pts with a diagnosis of TET discussed in French national or regional tumor boards. A expert pathological panel reviews all cases discussed during NHTBs. We analyzed epidemiological, clinical and pathological characteristics of pts.
Results
From January 2012 to December 2019, 2909 pts were included in the database. The median age at diagnosis of TET was 60 (range of 14-87), 53.6% were male. About 24% of the pts tumor samples (n=701) were centrally reviewed. In this subgroup of patients, the % of AID was overall similar to the whole cohort, 139/701 (19.8%). Three pts (2%) had more than 1 AID. Among the events, 96 were myasthenia gravis (MG) (69%), 9 Good’s syndrome (6.7%), 5 pure red cell aplasia (3.5%), 7 thyroiditis (5%) and 8 lupus (5.7%). Among pts presenting AID in the cohort (n=701), B2 was the most common subtype before and AB after central review, respectively. Before and after central review, the prevalence of different subtypes is shown in the table. Table: 1899P
Prevalence of AID per subtype comparing results from the Global cohort and before and after a central review
| Histology | Global cohort | Review cohort | ||||
| N (AID cohort/ Global cohort) | Prevalence (%) | N (AID with local Dx) | Prevalence (%) | N (AID/ Reviewed cohort) | Prevalence (%) | |
| Overall | 364/2909 | 12.5% | 139/701 | 19.8% | 139/701 | 19.8% |
| A | 10/81 | 12.3% | 6/42 | 14% | 3/34 | 8.8% |
| AB | 48/225 | 21.3% | 17/107 | 15.8% | 26/156 | 16% |
| B1 | 35/130 | 26.9% | 16/67 | 23.8% | 12/43 | 27.9% |
| B2 | 133/295 | 45% | 47/126 | 37.3% | 37/114 | 32.4% |
| B3 | 46/113 | 40.7% | 25/61 | 41% | 19/50 | 38% |
| C | 16/275 | 5.8% | 6/108 | 5% | 4/118 | 3.3% |
Conclusions
Around 1 out of 5 TET patients present an AID. The highest prevalence of AID after pathological central review was in B3 then B2 and B1 subtypes. Immunotherapy should be restricted to thymic carcinoma where the rate of AID is the lowest (3.3%).
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Gustave Roussy Cancer Center.
Funding
Has not received any funding.
Disclosure
M-É. Boucher: Advisory/Consultancy: AstraZeneca. All other authors have declared no conflicts of interest.