How do you manage a patient with cervical cancer who has FDG uptake in bilateral ischial tuberosities with lytic areas on CT correlate, and also has a history suspicious for untreated polymyalgia rheumatica with chronic symptoms in the same anatomic locations?

I would be very interested in the opinion of a rheumatologist regarding the etiology of the lytic disease in the ischial tuberosities. A decision should be made on whether to biopsy one of these lesions. My suspicion is that it is unrelated to cervical cancer, but that possibility needs to be considered. Assuming it is not related, I would manage the patient with curative-intent chemo-RT, as would be appropriate for any stage III cervical cancer. If these lesions represent metastatic disease, then chemo-RT is still most likely indicated (including the bony metastases) but with an understanding that treatment is palliative.

The question raises the concern for paraneoplastic PMR, an interesting subject in and of itself. Standard texts reference this relationship, especially in relation to multiple myeloma and Waldenström’s macroglobulinemia. One study (Muller et al., PMID 23842460) reports a 69% risk of the diagnosis of cancer in the first 6 months for GU, lymphatic, hematological, nervous system, and female reproductive system, while subsequent studies (Pfiefer et al., PMID 26688777) fail to support this association.

In either case, your case suggests pelvic-related pathology and there is a suggestion that there may be shoulder pathology to support the diagnosis of PMR. An ultrasound of the shoulder region and hip region would help here, as findings of (bilateral) subacromial subdeltoid bursitis, biceps tenosynovitis, shoulder GH synovitis, hip joint synovitis, and/or trochanteric bursitis would help establish a tissue-based inflammatory response consistent with polymyalgia rheumatica, distinct from the lytic lesions.

If you have evidence of inflammation in the shoulder girdle as well as the hip girdle, I would recommend discussing the use of low-dose prednisone with the treating oncologist and radiation oncologist. Frequently, with paraneoplastic autoimmunity, the associated physicians will support adding prednisone therapy for palliation of symptoms for the benefit of the patient’s symptoms.

I agree with starting with a biopsy given the history and potential for non-oncologic reasons for FDG uptake. I think I (and you) want the patient to not have metastatic disease, but it is worth making a good-faith attempt to 'prove it' in this scenario.

If biopsy is negative, treat the pelvis with definitive intent.

If positive, would first discuss with Gyn Onc or Med Onc about consideration of upfront systemic therapy. I personally prefer to start with systemic therapy with CarboTaxolAvastin +/- Pembro in these cases prior to consolidating with radiation as per below.

I would prefer to treat in a more aggressive manner than recommended by Dr. @Dr. First Last, as we otherwise would try for in recent history for oligometastatic cervical cancer.

I generally treat pelvic bone mets (when treating concurrently to definitive volumes) with nodal SIB-style dosing using principles of non-spine bone SBRT. FDG avid area + lytic/sclerotic region 'GTV' goes to 55-60, with a 1cm 'CTV' limited to bone (assuming no extraosseous extension) + 3-5 mm PTV getting 45 Gy, both in 25 fractions.

Patients will be at higher risk of at least acute bone marrow toxicity from this and should be counseled accordingly, especially in terms of the brachytherapy plan. Would also counsel on a higher than normal risk of pelvic insufficiency fracture.

In this clinical scenario, lytic lesions in the ischial tuberosities require us to assume they are due to metastatic disease. This does not rule out the possibility of concurrent PMR. Although PMR can sometimes be isolated to the hip girdle area, I would seek additional information. For example, does the patient have any shoulder girdle involvement?

The elevated markers for inflammation could be related to the cancer diagnosis or to PMR. A trial of low-dose steroids may provide symptomatic relief and would not interfere with any anti-cancer therapy. I would not delay treatment of the metastatic disease.