METHODS
The medical records of patients with adult RMS who were ?18 years old and treated with RT between
January 1995 and August 2016 in four different radiation centers were evaluated in terms of clinical
characteristics, treatment, and follow-up data retrospectively.
RESULTS
There were 28 patients. The median age at diagnosis was 28 (19-53) years. The most common site of involvement
was the head and neck (25%), and parameningeal region involvement was prominent (92%)
among them. In general, unfavorable site of involvement was markedly higher than favorable ones (82%
vs. 18%). Alveolar and pleomorphic subtypes compromised 75% of the cases. Fifteen patients had surgery,
26 chemotherapy, 10 radical intent of RT, 9 adjuvant, 3 preoperative, and 6 palliative. The follow-up
time was from 3 to 235 (median 18) months, disease-free survival was between 2 and 48 (median 12)
months, and 5-year overall survival (OS) was 25% (median OS 20 (4-235) months). There were significant
differences in terms of survival according to histopathological subtypes (p: 0.017), risk groups
(p<0.001), Intergroup Rhabdomyosarcoma Study Group (IRSG) grouping and IRSG staging (p<0.001).
CONCLUSION
Adult RMS has unfavorable clinical presentation and worse outcome compared with pediatric RMS.
Histopathological subtype and risk grouping to define the prognosis used in pediatric cases also might
be valid in adult RMS.
Keywords: Adult rhabdomyosarcoma, Soft tissue sarcoma, Treatment, Outcomes
The main aim of the present study was to better understand the clinical characteristics, treatment approaches, and outcomes of patients with adult RMS who received RT as a component of their multidisciplinary management since there are scarce data on adult RMS. The secondary aim was to evaluate the reliability of risk grouping and prognostic significance of histopathological subtypes in adult RMS.
History and physical examination were the first evaluations made for all patients. Local extent of lesions was mostly evaluated by computerized tomography (CT). Magnetic resonance imaging directed to the primary lesion was available in 67.8% of the patients. Bone marrow aspiration and/or biopsy were performed in 28.5% of the cases. Cerebrospinal fluid examination was done in 25% of the cases with head and neck in volvement. Since 2010, positron-emission tomography/ CT was performed in 42.8% of the patients.
Parameningeal site was described as middle ear,
nasopharynx, paranasal sinuses, infratemporal and
pterygopalatine fossa, and parapharyngeal region.[
Favorable sites of involvement were defined as orbit/
eyelid, head and neck (excluding parameningeal),
genitourinary (excluding prostate and bladder), and
biliary tract. Unfavorable sites were defined as parameningeal,
bladder, prostate, trunk, extremity, retroperitoneal,
pelvis, and others.[
Compartment surgery was defined as resection of
the entire tumor with its original compartment,[
Following completion of their treatments, patients
were followed up by 3-month intervals for the first 2
years, 6-month intervals for the next 3 years and then
annually afterwards.
Local control, disease-free survival (DFS), overall
survival (OS), and acute and late side effects were defined
as study end-points. Relapse was defined as any
clinicoradiological evidence of tumor recurrence. DFS
was calculated from the time of pathological diagnosis
to the relapse (locally or distantly) time. OS was calculated
from the date of diagnosis to the event-free final
follow-up or to the date of death of any cause.
Statistical Analysis
Continuous data were expressed as mean (SD) when
normally distributed and compared with Student's ttest
and median (25th-75th percentiles) when skewed
distributed and compared with Mann-Whitney U test.
Normality was evaluated by the Shapiro-Wilk test.
Categorical data were expressed as numbers (%) and
compared with Fisher's exact test. Time to event analysis
was performed by the Kaplan-Meier method, and
comparisons were done by log rank test. A two-sided p
value <0.05 was considered as significant.
Table
Fifteen patients had surgery, four of them being non-compartment. Among six patients who had positive surgical margins initially, re-resection was performed in one patient, and negative surgical margin was achieved. As a result, final surgical margin was positive in five patients.
2D RT planning was used in 3, 3D conformal RT in 8, and IMRT in 17 patients. RT was administered to the primary site with radical intent in 10, adjuvant in 9, preoperative in 3, and palliative in 6 patients. The median RT dose was 50 (16-70) Gy (95% confidence interval (CI): 45?54), and fractionation dose was from 180 to 800 (median 180) cGy (95% CI: 180-200). In 46.8% of the patients, excluding palliative ones, RT was started in the first 12 weeks (early RT) of the initial treatment. All patients were able to complete their RT schedules. Concurrent CT was administered in 46.8% of the cases. All patients received systemic multiagent CT except two. The most frequently used agents were vincristine (V), actinomycin D (A), ifosfamide (I), and cyclophosphamide (C). The most commonly used combinations were VAI, VAC, and VA (64.2%). Other agents used were doxorubicin, etoposide, mitomycin C, and cisplatin.
Locoregional recurrence was detected during their course of the disease in 17 (60.7%) cases, 5 were infield, and 2 were marginal. Local recurrences were significantly higher in patients receiving <41.4 Gy (p: 0.041). There was local recurrence in all of the five cases who had positive final surgical margins. During follow- up, 9 patients out of 19 (47%) who were M0 at the time of diagnosis developed distant metastasis, mainly to the lung. In all cases except one, the reason of death was related to cancer. At the time of analysis, there were five patients who were alive.
Follow-up time ranged from 3 to 235 months, with a median of 18 months (95% CI: 15?20). DFS was between 2 and 48 months, with a median of 12 months (95% CI: 7-16). The 5-year OS was 25%, with a median OS of 20 months (95% CI: 16?23) ranging from 4 to 235 months. By the end of the study, there were five patients who were alive.
There were significant differences in terms of survival
according to histopathological subtypes (p: 0.017),
risk groups (p<0.001), IRSG grouping (p<0.001), and
IRSG staging (p<0.001). Figs.
Age, tumor size, invasiveness of tumor, site of involvement, and presence of N1 disease at the time of diagnosis were not prognostic for outcome. M1 disease at presentation was significantly lower survival than M0 disease (13 vs. 23 months, log rank p<0.001).
In our study, the 5-year OS was 25% and is in line
with previously published data, which changes between
20% and 40%.[
The clinical presentation of our patient cohort was
relatively unfavorable compared with pediatric cases
that closely parallel with the literature in adult RMS.
[
A very high rate (82%) of unfavorable site involvement
was defined in our study, which is in line with
67% and 79% reported by Gerber et al. and SEER data,
respectively.[
There has been a controversy on the prognostic significance
of histopathological subtype in adult RMS. In
three retrospective studies, there was no any association
between histological subtype and survival; in the
study by Little et al., there was lower metastasis-free
survival in embryonal subtype that did not translate
to DFS.[
Furthermore, we have shown that survival was significantly
different according to risk group stratification
used in pediatric RMS. As a result, risk stratification
used in pediatric cases also might be valid in adult
RMS. However, there is controversy in the literature
about the use of childhood risk grouping in adults.[
Although risk-specific approach to staging has been
used in pediatric cases,[
RMS has the higher propensity for lymph node
metastases among other soft tissue sarcomas. The rate
of clinical presentation with lymph node metastases
was 32% in our patient cohort. This rate is in concordance
with other adult RMS series[
Adult RMS has higher distant metastasis rate than
pediatric RMS (15%).[
Although adult RMS is more radiosensitive than
most adult sarcomas, it is probably less sensitive than
pediatric RMS.[
Limitations of the study: The retrospective nature
of the study and relatively small number of patients
treated over a long period are the major limitations of
our study. The absence of central histological re-review
of archived materials is another limitation since there
has been improvement in immunohistochemistry recently.
Furthermore, we could not analyze the details
of CT schemes, duration, and dose intensity because of
the retrospective nature of the study.
Since it is unfeasible for adult RMS to proceed controlled, prospective trials because of its rarity, we should rely on these retrospective series and information from pediatric series except those with pleomorphic RMS.
Peer-review: Externally peer-reviewed.
Conflict of Interest: None declared.
Financial Support:None
Authorship contributions: Research Conception/ Design
- E.K.K., F.A., F.Ö.D., S.K.; Data Acquisition - E.K.K., A.İ.,
A.E., B.A., F.A., F.Ö.D., E.D., Y.A., S.K.; Data Analysis/Interpretation
- E.K.K., A.İ., A.E., B.A., F.A., F.Ö.D., E.D., Y.A.,
S.K.; Manuscript Preparation - E.K.K., A.İ., A.E., B.A., F.A.,
F.Ö.D., E.D., Y.A., S.K.; Final Approval - A.İ., A.E.,B.A., F.A.,
F.Ö.D., E.D., Y.A.; S.K.