Methods
A retrospective study of patients with thymic tumours treated in our
Institution between 1985 and 2019 was performed. All consecutive
patients with thymic tumours younger than 18 years old were included
into the study.
The following parameters were included in the analysis: date of
diagnosis, primary tumour characteristics, given curative treatment,
performance status, systemic therapy, RTH characteristics - total dose,
irradiated volume, early and late toxicity, local response, date and
reason of death. Missing dates of deaths were obtained from the Polish
National Cancer Registry.
The criteria for diagnosing thymoma or thymic carcinoma used were as
established by the WHO classification [10] (Table 1). Tumours were
staged according to the commonly-used Masaoka-Koga staging system
[11,12] (Table 2). Eastern
Cooperative Oncology Group (ECOG) scale was used to classify patients’
performance status. EORTC/RTOG toxicity criteria were used to assess
treatment morbidity [13]. Tumour response was classified, as
follows: complete regression (CR)
was defined as complete disappearance of all clinical and radiological
evidence of the disease, partial
regression (PR) as a decrease of tumour size in clinical or radiologic
evaluation and progression as increase in lesion size or occurrence of
new lesions.
Median follow-up was estimated by Kaplan-Meier analysis with the
reversed meaning of the status indicator.
Overall survival (OS) was
calculated from the date of disease diagnosis to the date of last
follow-up or death. Progression
free survival (PFS) was calculated from the date of diagnosis to the
date of local/distant progression or death. The Kaplan-Meier method was
used to estimate survival. Statistical analyses were performed using
Statistica 12.0.
A total number of 8 children (4 boys and 4 girls) with thymic tumours
were identified. Median age at diagnosis was 7 years (range 1 to 18). In
all the cases, the diagnosis was based on diagnostic imaging and
pathologic examination of the tumour tissue samples obtained during the
surgery. In 4 cases, tumour was found on a
computed tomography (CT) of the
chest and in 4 cases (treated in the earlier years of a study) on the
chest X-ray. Mean tumour dimensions were 82 x 62 x 93 mm and the tumours
ranged from 50 to 135 mm in the greatest dimension. In 3 patients tumour
showed contrast enhancement, in 4 cases tumour was constricting nearby
organs and in 1 case infiltration of surrounding tissues was described.
In one patient lung metastases were diagnosed simultaneously with
primary tumour.
All patients had histopathologic confirmation of thymic neoplasm – in 7
of them thymoma was diagnosed, in 1 thymic carcinoma. In 5 of them WHO
type was assessed – in two of them B1 type was found, in one B2, in one
AB and in one C. Tumours were staged according to the commonly-used
Masaoka-Koga staging system in 5 cases – stage II in one, stage III in
three and stage IV in one.
ECOG scale was used to classify patients’ performance status and all but
one patient were in a good performance status at the time of the
diagnosis (ECOG 0-1). Symptoms of the disease were present in 5 of them
and lasted for 1 to 24 months – weakness in 3 of them, dyspnea in 1,
cough in 2, weight loss in 2 and fever in 2. Other symptoms presented
individually were: doubled vision, oedema of the neck and face and
palpable neck tumour. In one patient diagnostic was introduced due to
the lung infection. None of them presented with myasthenia.
All the patients were treated with radical intention. The
characteristics of the treatment used in particular patients are
presented in Table 3. In all but one surgery was the first-line
treatment, however only in two cases a complete removal of the tumour
was performed and other patients had partial resection. One patient
started treatment with CTH and four others received CTH after the
surgery. In one patient CTH was combined with RTH. Systemic treatment
applied was: ADOC (doxorubicin 40mg/m2 + cisplatin
50mg/m2 + vincristine 0.6mg/m2 +
cyclophosfamid 700mg/m2) – in 3 patients; cisplatin +
adriamicin + bleomycin + encorton in 2 patients, VIP (etoposide
75mg/m2 + cisplatin 20mg/m2 +
ifosfamide 1.2g/m2) in 1 patient and PACE (cisplatin
50mg/m2 + doxorubicin 50mg/m2 +
cyclophosfamid 500mg/m2) in 1 patient. In 2 of them
ADOC was followed by VIP and in one by cisplatin + adriamicin +
bleomycin + encorton. Usually six cycles of CTH was applied.
RTH was applied to median total dose of 37.5 Gy. Radiotherapy
characteristics is presented in Table 4. In all patients conformal
technique (two or three fields’ technique) was used. Irradiated volume
(CTV, clinical target volume)
included mediastinum in 4 patients combined with boost on lung
metastasis in stage IV patient and with tumour bed boost and chest lymph
nodes irradiation in 1 patient, tumour in 1 patient and tumour bed in 1
patient. Planned target volumes
(PTVs) were created by adding additional margins to CTV in order to
correct for inaccuracies in the delivery system (set-up margins) or
interfraction and intrafraction of organ motions.