Neuropathic Pain due to Fibromatosis: Does Anticancer Treatment Help?

Desmoid fibromatosis, although histologically benign, infiltrates local structures. The involvement of neural structures can lead to difficult neuropathic pain and the escalating use of analgesics. We report a patient with desmoid fibromatosis of the chest wall causing brachial plexus infiltration. As the tumor was locally invasive and unresectable, he was treated with radiation therapy and oral tamoxifen. On follow-up, there was significant pain relief, sustained reduction in the tumor size, and reduced analgesic requirement. Antineoplastic treatments like local radiation therapy and targeted systemic therapy with hormones or other agents can be considered in the management of selected unresectable desmoid fibromatosis to improve symptom control and reduce polypharmacy.

INTRODUCTION

Patients with the involvement of the brachial or lumbosacral plexus or other causes of neuropathic pain often need escalating doses of opioids and adjuvants. Despite this, some patients may experience refractory pain as well as the side effects of multiple analgesics. Palliative radiotherapy is therefore often used for pain relief in malignant conditions such as Pancoast tumor and metastatic spinal cord compression.

This case report illustrates the role of antineoplastic treatment in a locally aggressive but nonmalignant tumor, where it was possible to relieve pain, reduce analgesics, and shrink the tumor, even though surgical excision was not possible.

CASE REPORT

A 45-year-old man presented with right-sided chest pain and pain in the right upper limb since 2 years, with a recent onset of paraesthesia in the medial two fingers. He also had right-sided Horner's syndrome.

Imaging revealed a superior sulcus mass measuring 6 × 6 × 11.5 cm, infiltrating the chest wall and eroding the posterior ends of the first three ribs. It was involving the C8 and T1 nerve roots and the brachial plexus. The CT-guided biopsy was consistent with desmoid fibromatosis. There was no definite staining for CD117 on immunohistochemistry.

Since it was an inoperable desmoid tumor, the patient was treated with radiation therapy, 45 Gy administered in 25 fractions. He was started on oral tamoxifen 20 mg once daily.

On the first follow-up, 3 months after radiotherapy, the patient was referred to the Palliative Care Unit with persistent pain. He was treated with diclofenac 50 mg three times daily, amitriptyline 50 mg hsod and dextropropoxyphene 1 q6h and prn. Three days later, because of persistent pain he was given a single dose of dexamethasone 8 mg, and the weak opioids, adjuvants, diclofenac and tamoxifen, were continued. It was planned to increase amitriptyline, but the patient was from a distant part of the country and returned only after 6 months. During this period, he had taken imatinib for 3 months, and analgesics and tamoxifen for 6 months. On the second follow-up 8 months after radiotherapy, his ptosis had improved; the doses of opioids and antidepressants were therefore reduced and tamoxifen was continued. The patient next returned 2 years after radiotherapy. Since the pain was very mild and the tumor had reduced by more than 50% [Figure 1], analgesics were further reduced to paracetamol 500 mg three times daily and one capsule of dextropropoxyphene at night. Tamoxifen was continued.

Figure 1a and b

Reduction in the right apical tumor at 2-year follow-up

DISCUSSION

Desmoid fibromatosis: Local therapy

Desmoid tumors are histologically benign neoplasms, being a monoclonal proliferation of cytologically benign fibrocytes[1] arising from musculoaponeurotic structures. The most common sites are the abdomen and the chest wall.[2] Desmoid tumors do not metastasize, but since they lack a pseudocapsule, they can infiltrate local structures and have a high risk of local recurrence, even after major surgical resections.

Recurrences occur due to ill-defined margins of infiltration along the septal planes, and it is difficult to estimate adequate surgical margins. Radiotherapy can permit less mutilating surgery, and can also serve as the primary mode of treatment in unresectable tumors.[3] In a survey of 110 patients with a median follow-up of 6 years (range 1–44 years), Baumert et al. reported that the addition of radiotherapy significantly reduced local recurrences compared to surgery alone (hazard ratio 0.19).[3] With surgery and postoperative radiotherapy, the progression-free survival was 95% at 5 years and 93% at 10 years. Patients are likely to survive many years, and short courses of hypofractionated palliative radiotherapy could result in significant late toxicities. Appropriate fractionation is necessary and a radiotherapy dose of more than 50 Gy can provide better tumor control.[3]

Desmoid fibromatosis: Systemic therapy

The natural history of this disease remains difficult to predict. Some patients progress despite locoregional treatment, and systemic therapy may be worthwhile. To date, there are no randomized trials of systemic therapy but a retrospective analysis by the Memorial Sloan Kettering Center studied 68 patients. Although a variety of systemic therapies had been used including NSAIDs, chemotherapy, and imatinib, the best response rates were observed with anthracyclines and hormonal therapy, with only 12% of tumors showing disease progression.[2]

The patient in this case report appeared to benefit from systemic therapy with tamoxifen. Chao et al. reported the complete response of a recurrent pelvic desmoid tumor to 7 months of tamoxifen with the response sustained at a follow-up of 6 years.[4] Tamoxifen was first used by Kinzbrunner in recurrent, large painful desmoid lesions, based on the observation that desmoid tumors were common in women in their childbearing years and reduced after menopause. He observed a complete relief of pain within a week and 50% reduction in tumor size.[5]

In a systematic review of pharmacological therapies, Janinis et al.[6] summarized the results with hormonal agents, NSAIDs, targeted therapies, and chemotherapy. Responses to systemic therapy and radiotherapy are often delayed by many months, as in our patient, where we did not see much benefit at 3 months, but the tumor continued to shrink at 1-year and 2-year follow-ups. Hormonal therapies and/or NSAIDs are recommended as first-line systemic therapy since toxicity is less than that with chemotherapy. If the tumor is not causing significant problems, and is stable in size, it may be appropriate to continue current therapies or watch and wait rather than embark on heroic surgeries, or toxic or expensive systemic therapies.[7] Wilcken et al.[8] have reported benefit with the use of progesterones as second-line hormonal therapy.

CONCLUSION

Brachial plexopathy and other types of difficult neuropathic pain are a challenge in the palliative care setting. Disease-directed therapy can reduce pain and the need for polypharmacy. Radiation therapy for achieving good symptom relief can be worthwhile in locally aggressive but nonmetastasizing neoplasms such as desmoid fibromatosis. Affordable targeted systemic therapies including hormonal treatment may have a role even in patients who are frail and who have relapsed on earlier anticancer therapies.