CUH Radiology guidelines

These guidelines are for solid tumours in teenage (16+), young adults, and adults only. Separate guidelines cover haemato-oncology patients.

Best practice is that patients for whom WGS may be of benefit should be identified and discussed in advance at a multidisciplinary team (MDT) meeting.

Eligibility

Please see current guidance (opens in a new tab). The commonest indications for WGS are currently:

1. Age 16-24 and any lesion that could be malignant
2. Any age and sarcoma is in the differential (based on clinical/radiological features at site-specific MDT) OR histologically confirmed sarcoma
3. Any age, advanced tumour that has exhausted standard of care testing and treatment options (including carcinoma of uncertain primary)
4. High-grade tubo-ovarian carcinoma

Consent

• WGS consent by trained member of the clinical team, this must be done prior to the biopsy being requested or samples collected.
• An electronic record of discussion must be completed to allow visibility for all professionals in the pathway, and this must be confirmed prior to the biopsy procedure.
• Where tissue is being acquired for both histological diagnosis and WGS, biopsy procedure consent must include discussion of WGS cores as optional in addition to diagnostic cores.

Radiological biopsy procedure

• For an estimated 90% WGS success rate the GLH require 50mm³ of tissue (of which at least 30% is lesional).
  • 50mm³ is equivalent to 40mm length of tissue using a 16g needle, or 80mm with an 18g needle.
• The SmartTexts contain recommendations on the quantity of tissue taken at biopsy. They are guidance - the operator should weigh up risks and benefits considering e.g., location and vascularity of the tumour, as well as patient comfort during the procedure.
• They may not be appropriate for e.g., intrapulmonary biopsies but could be considered for most other lesions.

Handling and submitting the specimen

Routine (in hours <4pm)

• The entire specimen should be submitted fresh (in saline or dry pot)
• Fresh samples should be portered to the Histopathology department immediately after the biopsy (if there is a delay, samples can be stored temporarily at 4oC).

Out of hours (>4pm, Bank holidays + weekends)

• If the specimen is being taken solely for WGS, the specimen should be submitted in RNAlater (which preserves nucleic acid at room temperature)
• If this is a combined procedure where routine histopathology and WGS are both required, the specimen must be divided into two separate pots, one for WGS containing RNAlater (which preserves nucleic acid but renders the specimen unsuitable for routine histopathology) and one containing formalin (for routine histopathological diagnosis). Routine diagnosis is always the priority, and at least two good cores should be submitted in formalin, with the remainder submitted in RNAlater.
• Both the formalin and RNAlater specimens can be sent to histopathology at room temperature

Request process

• Biopsy request should include the phrase “see comment"
• In the comments section please use the appropriate SmartText
  • WGSSOLIDRADBXFRESH where tissue is needed only for whole genome sequencing.
  • WGSSOLIDRADBXFIXANDFRESH where tissue is needed for WGS and histopathology.
  • Separate SmartTexts exist for haemato-oncology patients, please refer to the haemato-oncology guidelines.