Radiotherapy For Extremity Sarcomas

Radiation therapy plays a crucial role in the multidisciplinary management of extremity soft tissue sarcomas, aiming to achieve optimal local control while preserving limb function. For Stage I disease, wide surgical excision with ≥1 cm margins is often curative. Stage II–III tumors require a combination of surgery and radiotherapy—either preoperative (50 Gy) or postoperative (60–66 Gy)—with consideration of chemotherapy for large, deep, or high-grade lesions. In unresectable cases, definitive radiotherapy (70–80 Gy) or concurrent chemo-RT may downstage tumors for resection. Field design and dose planning follow MRI-defined margins, with emphasis on sparing critical structures such as skin, bone, and joints. IMRT is preferred for dose conformity and tissue preservation, while IORT and brachytherapy provide localized dose escalation when indicated. Despite high local control rates (~90%), complications such as wound dehiscence, fibrosis, edema, and fracture remain clinically significant. Long-term surveillance with MRI and chest CT is essential due to recurrence and metastasis risk

Timing & Technique

· Postoperative EBRT: Start 10–20 days after surgery

· Preoperative EBRT: 42,75 Gy in 15 fraction or 50 Gy in 25 fraction, surgery follows ~3 weeks later

· Post-op Brachytherapy: ≥6 days post-op

· Post-op IORT: During surgery

Field Design

· Post-op: Tumor bed, scar, drain sites + margins (4 cm longitudinal, 1.5 cm radial)

After 50 Gy: Reduce field to surgical bed + smaller margins (+ 2 cm longitudinal, 1.5 cm radial)

· Pre-op: Tumor (MRI T1 postcontrast) + 4 cm longitudinal, 1.5 cm radial + suspicious edema (MRI T2)

Dose Limitations

20 Gy: Risk of premature epiphyseal closure
≥40 Gy: Bone marrow ablation
≥50 Gy: Bone fracture risk
Limit bone V40Gy < 64%, reduce mean bone dose

Critical Structures to Spare

1.5–2 cm strip of skin
Skin over anterior tibia
½ of weight-bearing bone cross-section
Major tendons and joint cavities
Avoid treating full extremity circumference >50 Gy

Technique Tips

IMRT preferred for better tissue sparing
Frog-leg position for upper inner thigh
Prone position for buttock/posterior thigh
No elective nodal radiation; gross nodes should be resected

Brachytherapy

Catheters placed 1 cm apart in OR.
Loaded ≥6 days post-op for healing.
Target: tumor bed + 2 cm longitudinal, 1-1.5 cm circumferential margin

Special Considerations

If using doxorubicin: reduce dose/fraction (1.8 Gy), delay RT >3 days
Use gonadal shielding to preserve fertility
Early physical therapy improves outcome

Complications

Wound healing issues: 5–15% post-op RT vs. 25–35% pre-op RT.
Bone/soft tissue growth abnormalities.
Limb length discrepancy (2–6 cm).
Fracture risk within 18 months.
Fibrosis, lymphedema, dermatitis, telangiectasia.
5% risk of secondary malignancy.

Follow-Up

First 2 years: Exams + MRI of primary + CT chest every 3 months
Years 3–5: Every 6 months
After 5 years: Annually
Ultrasound for superficial lesions.
Bone scan or PET if clinically indicated

Heterotopic Ossification

Indications: Used perioperatively for patients with prior heterotopic ossification, diffuse idiopathic skeletal hyperostosis, or hypertrophic osteoarthritis—especially when indomethacin is contraindicated.
Timing: Administered <24 hours before surgery or <72 hours after.
Include soft tissue around joint space.
Blocking surgical hardware is controversial.
Dose and fractionation: 7 Gy in single fraction via AP/PA fields.

References

· Springer International Publishing AG, part of Springer Nature 2018 , Eric K. Hansen and M. Roach III (eds.), Handbook of Evidence-Based Radiation Oncology, https://doi.org/10.1007/978-3-319-62642-0_39

· Demos Medical, Videtic, Gregory M. M., Vassil, Andrew D., Woody, Neil III (eds.),Handbook of treatment planning in radiation oncology , Third edition. New York, NY, [2021]

· Springer Nature Switzerland AG 2022 1. N. Y. Lee et al. (eds.), Target Volume Delineation and Field Setup, Practical Guides in Radiation Oncology, https://doi.org/10.1007/978-3-030-99590-4

Conventional osteosarcoma of the left thigh encasing femoral vessels and invading muscle planes; managed with left hip disarticulation after multidisciplinary evaluation.

STAGE	TREATMENT	5- YEAR OUTCOMES
Extremity Stage I	Surgery alone if margins ≥1 cm	LC: 90–100%OS: 90%
Extremity Stage II–III	Pre-op RT → surgery or surgery → post-op RT. Consider neoadjuvant/adjuvant chemo for large, deep, high-grade tumors. For local recurrence (LR): amputation can salvage ~75%	LC: ~90%OS: 80% (Stage II), 60% (Stage III)
Extremity Stage IV	If controlled primary + ≤4 lung mets or long disease-free interval → surgery + metastatectomy Otherwise: best supportive care, chemo, palliative surgery or RT	OS: ~25% OS: ~10%
Extremity Unresectable	Definitive RT (70–80 Gy), chemo (Doxorubicin + Ifosfamide), or chemoRT. Surgery if becomes resectable
Retroperitoneal	Surgery + IORT (12–15 Gy) → post-op EBRT (45–50 Gy) or pre-op RT ± chemo → resection ± IORT boost	LC: ~50% DM: 20–30% OS: ~50%
GIST	Resectable: surgery → imatinib (or observation if completely resected). Unresectable: imatinib → surgery → imatinib
Desmoid Tumors	Surgery. R0: observe. R1: re-resect or observe. R2/inoperable: RT (54–58 Gy). Consider chemo/hormonal/targeted therapy

Treatment Recommendations

Condition	DOSE
Negative margins	60 Gy
Microscopic residual	60 Gy
Positive margins	66 Gy
Gross disease	70–76 Gy
Pre-op EBRT	50 Gy
Post boost (EBRT/IORT)	65–75 Gy
Post-op brachytherapy (R1)	14–18 HDR / 16–18 LDR
Post-op brachytherapy (R2)	18–24 HDR / 20–26 LDR
IORT	10–15 Gy

Dose Guidelines

Synovial sarcoma was confirmed through imaging and biopsy. The patient underwent limb-salvage surgery with wide excision and free flap reconstruction.