Date post: | 26-May-2015 |
Category: |
Health & Medicine |
Upload: | yong-chan-ahn |
View: | 122 times |
Download: | 1 times |
Technical Progress and Role of
External RT in Thyroid Cancer
Yong Chan Ahn, MD/PhD Dept. of Radiation Oncology
SMC/SKKU SOM
In Treating Thyroid Cancer…
• Role of ERT has been proven in adjuvant,
salvage, as well as palliative settings.
• ERT, however, has been under-used than it
is needed, mainly in fear of annoying side
effects.
• With technical progress in ERT (IMRT,
IGRT) patients could get more benefit.
1. Is ERT effective in thyroid cancer?
2. What are indications of ERT?
3. What are problems of ERT?
4. Can new RT techniques be answer?
Case
• *** (F/76)
• CC: swallowing discomfort, hoarseness
Definitive high dose ERT alone
’09/3/31~5/28: 70 Gy/35 fractions by 3D conformal RT
’11/4/1 ’09/3/17
’11/10/11 ’09/3/20
1. Is ERT effective in thyroid cancer?
2. What are indications of ERT?
3. What are problems of ERT?
4. Can new RT techniques be answer?
IJROBP (2002)
• 1,057 DTC patients @ QEH (1960~1997)
842 patients (79.7%) had PTC
215 patients (20.3%) had FTC
• ERT (60 Gy/30 Fx’s) to thyroid bed and lymphatics if
gross LR disease in neck, extensive extrathyroidal
extension, extensive LN metastases
Summary @ QEH
• ERT reduced LR failure risk.
• In 124 patients with gross
residual improved LR control
rate by ERT (56.2% vs 24%,
p=0.0019)
• ERT to improve LR control is
indicated in patients with
gross postoperative residual
disease.
Clinical Endocrinology (2005)
• 729 DTC patients @ PMH (1958~1998)
’58~’71
(127)
’72~’85
(250)
’86~’98
(352)
Total
(729)
RAI Yes 59 (46%) 159 (64%) 310 (88%) 528 (72%)
No 68 (54%) 91 (36%) 42 (12%) 201 (28%)
RT Yes 71 (56%) 113 (45%) 134 (38%) 318 (44%)
No 56 (44%) 137 (55%) 218 (62%) 411 (56%)
Surgery Total 16 (13%) 95 (38%) 294 (84%) 405 (56%)
Subtotal 40 (32%) 61 (24%) 21 (6%) 122 (17%)
Lob 53 (42%) 86 (34%) 25 (7%) 164 (23%)
Summary @ PMH
• ERT improved LRFR
and CSS in high-risk
patients.
J Clin Endocrinol Metab (2011)
• Established role of EBRT in DTC:
• In adjuvant setting: extensive ETE, repeated cervical
nodal recurrence
• In definitive setting: local recurrence requiring
extensive ablative surgery
• Careful selection of high-risk patients is required.
EBRT in DTC • American Thyroid
Association guideline:
– >45 years
– Grossly visible ETE
– High likelihood of
microscopic residual
disease
– Gross residual tumor in
whom further surgery or
RAI would likely be
ineffective
– Sequence of EBRT and
RAI depends on gross
residual disease volume and
likelihood of RAI
responsiveness
• British Thyroid Association
guideline :
– Gross evidence of local
tumor invasion at surgery
– Presumed significant
macro- or microscopic
residual disease
– Residual tumor fails to
concentrate sufficient
amounts of radioiodine
– Extensive pT4 disease
– >60 years
– Extensive extra-nodal
spread even without evident
residual disease
EBRT in DTC • Medullary Thyroid Cancer:
– Further single institutional
data supports use of ERT
in improving local control
in highly selected patients
with MTC.
– However, ERT should be
reserved only in patients at
high risk of devastating
cervical recurrence
requiring extensive
ablative surgery.
• Anaplastic Thyroid Cancer:
– Extremely poor outcome.
– Improved local control
with concurrent ERT
(hyper-fractionation) and
taxanes.
ERT as Palliative Tx
• Symptomatic skeletal metastases
• Brain metastases
• Hepatic metastases
• For relief of pressure symptoms by soft tissue
tumor in vital areas -- SVC syndrome
• Recurrent/metastatic tumor following RAI
• * ATC, MTC
1. Is ERT effective in thyroid cancer?
2. What are indications of ERT?
3. What are problems of ERT?
4. Can new RT techniques be answer?
Disadvantages of ERT
• Loco-regional Tx modality
• Not a selective Tx modality
• Long Tx duration (5~6 weeks)
• Dose-response relationship?
– Normal tissue tolerance limit have
been usually applied (50~60 Gy)
• Optimal RT target volume?
– Tumor bed + entire neck +/- upper mediastinum
Common Side Effects of ERT
• Aerodigestive track:
– Swallowing discomfort, pain, voice change, dyspnea,
cough, sputum
• Skin and soft tissue:
– Dermatitis, lymphedema, fibrosis, joint stiffness, soft
tissue necrosis
• Glandular structures:
– Dry mouth (dental caries), dry eye
• Skeletal system:
– Osteonecrosis, chondronecrosis
• Others:
– Fatigue, anorexia, nausea, second cancer
1. Is ERT effective in thyroid cancer?
2. What are indications of ERT?
3. What are problems of ERT?
4. Can new RT techniques be answer?
From 2-D to 3-D
Intensity Modulated RT
2D
3D
IMRT
Image Guided RT
Individualized
Customized
Adaptive
New RT Techniques
Precise
Accurate
Reliable
Therapeutic Ratio
New RT Techniques
• Intensity Modulated RT (IMRT)
– LINAC-based: step & shoot;
sliding window; volumetric arc
– Helical Tomotherapy
• Image-guide RT (IGRT)
• Stereotactic Body RT (SBRT)
RT Technique
• Combination of IMRT and IGRT may be
beneficial in reducing toxicity and improving
local control.
• IMRT and IGRT should ideally be employed
when treating thyroid cancer with EBRT.
In Treating Thyroid Cancer…
• Role of ERT has been proven in adjuvant,
salvage, as well as palliative settings.
• ERT, however, has been under-used than it
is needed, mainly in fear of annoying side
effects.
• With technical progress in ERT (IMRT,
IGRT) patients could get more benefit.