Role of CT in the detection and management of cancer related complications: a study of 599 patients

Purpose Cancer-related complications (CrC) and any potentially life-threatening findings detected on routine oncological imaging requires urgent intervention and needs proactive management. We conducted a retrospective study to highlight the role of imaging in the detection of CrC on computed tomography (CT)-scan while sharing our experience at a tertiary care cancer hospital. Materials and methods All the reports of the CT scans performed in our department between January 2018 and December 2019 were reviewed and the imaging findings of CrC were recorded. Only the patients who had known malignancy and underwent imaging evaluation at our centre at baseline/follow up/surveillance were included. The clinical details of the patients were recorded and the findings were classified based on the system or organ involved and also on the basis of its impact on clinical management. Results A total of 14,226 CT scans were performed during the study period, out of which 599 patients had CrC. Most of the CrC were seen involving thorax (265/599, 44.3%) followed by abdomen (229/599, 38.2%) and head and neck (104/599, 17.3%) regions. The commonly encountered CrC were pulmonary infections, superior vena cava obstruction and drug-induced lung changes. Conclusion CrC have significant impact on the course of management of cancer patients and radiologist plays an important role in early diagnosis and initiation of prompt management of many such patients. CT is an excellent modality for early diagnosis of CrC which guides the oncologist for appropriate treatment.


Introduction
Cancer has become one of the leading causes of morbidity and mortality in today's world [1,2]. Any acute potentially life-threatening event that occurs due to the malignancy or its treatment and requires urgent intervention can be labelled as an oncological emergency or complication. Such an event can occur at any time during the course of malignancy or sometimes can also be the initial presentation [3]. These can be attributed to direct effects of tumour progression or indirect effect. Direct effects include structural causes such as invasion or compression of adjacent viscera by the tumour. Indirect effects include metabolic and haematological changes which lead to systemic conditions like hypercalcaemia, tumour lysis syndrome, febrile neutropenia, hyperviscosity syndrome, and disseminated intravascular coagulation [4].
Imaging plays an important role in the detection of structural causes such as compression or infiltration of involved organs or haemorrhage or thrombosis of any major vessel [2]. Hence, the radiologist has to be vigilant to observe and inform about these findings to the treating physician in order to prevent their catastrophic effects [5]. Furthermore, incidentally detected pathologies like tumour rupture, ascites, pericardial effusion, pulmonary thromboembolism can have bearing on the treatment course in the form of modification or addition of drugs in the planned protocol. It is also imperative to differentiate and determine the treatment related changes like drug induced toxicity, which may have detrimental effect on patient outcome if not intervened at right time [6,7].
Radiograph, ultrasonography (USG) and computed tomography (CT) are commonly used modalities used for diagnosis and evaluation of most of these conditions [1]. Magnetic resonance imaging (MRI), on the other hand, is primarily indicated for complications related to central nervous system (CNS) like metastasis, cerebral herniation, intracranial haemorrhage and spinal cord compression [2]. Ultrasound-, fluoroscopy-and CT-guided various interventional procedures are used for management of various structural complications of malignancy [8]; for instance, percutaneous trans hepatic biliary drainage (PTBD), percutaneous nephrostomy (PCN), percutaneous gastrostomy and stenting to relieve malignant luminal obstruction [9]. On the other hand, vascular interventions are carried out with curative or palliative intent in the settings of unresectable hepatocellular carcinoma, tumour rupture, tumoural haemorrhage, etc [2,9]. This study has been conducted to highlight the role of CT in detection of cancer related complications (CrC) and oncological emergencies; while sharing our experience of tertiary care cancer hospital.

Materials and methods
The retrospective study was conducted after obtaining approval from the institute ethics' committee and the individual patient consent was waived off. The data had been collected from the CT reporting data base of our department.
All the reports of the CT scans performed between January 2018 and December 2019 were reviewed and the imaging findings of CrC were recorded. Only those patients, who had known malignancy and underwent imaging evaluation at our centre at baseline/follow up/surveillance were included. Out of total 14,226 CT scans performed on Somatom definition AS (Siemens, 64 slice scanner) during these 2 years, reports of 599 patient revealed imaging features of CrC and were included for further classification.
The demographic and clinical details of the patients were recorded and the findings were classified based on the system or organ involved and also on the basis of its impact on clinical management.
Classification of CrC based on the organ/system involved was broadly done under the groups of head and neck, chest and abdomen while the other classification was based on the impact of the finding under the categories as those warranting immediate intervention, elective intervention or which can be managed conservatively.
All the findings were then recorded and tabulated in word document. Continuous variables were presented as mean ± SD and categorical variables were presented as frequency and percentages.
CrC classification based on need of intervention: There were 355 (59.4%) CrC that needed either immediate medical, surgical or radiological intervention, which included ICT placement for pneumothorax; laparoscopy or open surgery for intestinal obstruction; treatment of pulmonary infection, which also led to interruption of routine treatment; etc. as documented in Table 3. Where chemotherapy or radiation induced changes (n = 124) required change in management strategy; complications like pulmonary haemorrhage (n = 14) or pulmonary thromboembolism (n = 13) needed additional treatment before proceeding with routine regime. The conditions like asymptomatic intussusceptions (n = 4) and radiation induced or tumour induced pelvic (vesicovaginal or rectovaginal, Figure 5g) fistulas (n = 6) were managed conservatively.

Discussion
Any potentially life-threatening event in cancer patients that occurs due to the malignancy or its treatment is considered an oncological emergency which needs early and aggressive management. Thus, it becomes imperative for the radiologist to identify and promptly communicate to the treating clinician for early intervention. They can be broadly classified as metabolic, haematological and structural conditions [10]. Metabolic and haematological emergencies including hypercalcaemia, hyponatremia, hyper viscosity syndromeor disseminated intravascular coagulation are mainly diagnosed in relation to laboratory findings [11]. Imaging especially cross-sectional imaging is performed to rule out structural causes of the symptoms. Multidetector CT is the most readily performed imaging modality for cancer patients at baseline, during treatment and post treatment follow up. In addition to the information related to the status of primary tumour, it is able to identify the sequel or changes due to the tumour or metastases or treatment being administered for the particular cancer.
In this study, we were able to highlight that, thoracic complications (265/599, 44.3%) were the most common CrCs which might be due to early presentation with debilitating symptoms like dyspnoea, fever, cough, hemoptysis which hampers patient's day to day life. Not only does the CT helps by ruling out underlying primary lung carcinoma but is also able to illustrate other infective or non-infective causes of the symptoms. Pulmonary infection (62/265, 23.4%) was the most common thoracic complications seen in our patients predominantly in patients receiving treatment for lymphoma and leukaemia (Figure 1). Presence of active infection, especially in post-marrow transplant patients, indicates addition of the antibiotics, antifungals or antivirals with interim discontinuation of the routine therapy (Figure 5a and b). On the other hand, pulmonary haemorrhage would need treatment with steroids which would need continuous monitoring of the patient. The other causes of dyspnea include pleural or pericardial effusion which would warrant immediate therapeutic drainage if compromising quality of life of the patient. Similarly, the chemotherapeutic agents like Bleomycin induce acute interstitial pneumonia which the oncologist should be aware of before planning the next regime. On the other hand, differentiation syndrome due to ATRA can present as features of pulmonary oedema leading to discontinuation of the drug [6]. Pneumothorax due to subpleural cavitatory metastases can lead to sudden deterioration of patient's clinical status and need immediate drainage with intrathoracic chest tube placement [12]. On the other hand, structural causes like SVC syndrome would need immediate initiation of chemotherapy to reduce symptoms and at times, patient might need balloon dilatation of the vein (Figure 2). Image guided interventions for cancer patients can be performed for treatment or palliative therapy. Obstruction of biliary system leads to hyperbilirubinemia which needs to be drained with PTBD so as to make patient fit for chemotherapy and cancer control. MDCT can identify the level and sequel of malignant obstruction of biliary, urinary, bowel and vascular system [13]. Urinary tract obstruction may progress to uremia and would need immediate diversion with PCN tube or a ureteric stent using USG and fluoroscopy guidance (Figure 5f). However systemic treatment post-stenting, cystoscopic evidence of bladder invasion and length of obstruction greater than 3 cm are associated with stent failure making PCN placement the preferred option in these conditions for decompression [14].
Similarly, the neurological symptoms caused due to brain oedema, cerebral herniation or cord compression are better delineated with MRI owing to its superior resolution; however, in our resource constraint setting, it is not possible to perform MRI in every patient and CT is preferred to rule out secondary changes of herniation and hydrocephalus [15]. Radiation induced laryngeal oedema can cause severe airway in 15%-50% patients warranting immediate intervention [16].
Abnormal fistulous communication between the oesophagus and the trachea, bronchi, and lung parenchyma occurs in lymphoma, oesophageal, and lung malignancies causing recurrent pulmonary infections and aspiration pneumonitis [17]. Site and number of fistulae as well as condition of underlying lung can be easily assessed with the help CT and new reconstruction algorithms like virtual endoscopy. This would need measures for rerouting the food intake of the patient by means of Ryle's tube, percutaneous gastrostomy or jejunal gastrostomy. Some patient would benefit from oesophageal and tracheal stent (Figure 5c and d); thus it becomes important for radiologist to highlight such complications in the report; in addition to staging of the carcinoma; so as to improve the quality of life of the patient. Rupture of hypervascular malignancies such as hepatocellular carcinoma, renal cell carcinoma and melanoma or splenic rupture in cases of hematological malignancies are well known causes of hemoperitoneum. The interpreting radiologist can highlight the cause of active contrast extravasation which can help in planning embolisation and achieving haemostasis (Figure 5e) [18]. Hypercoagulable state in malignancy due to prothrombotic factors released by cancer cells has been implied in thrombosis and infarct related acute emergencies such as mesenteric ischemia and solid organ infarct [19]. Multiphase CT can demonstrate the primary mass, status of mesenteric vessels, and any associated abnormal enhancement or bowel thickening [4]. Chemotherapy induced pancreatitis is most commonly associated with L-asparaginase ( Figure 4c) used for treatment of leukaemia and sorafenib used for metastatic RCC [6]. Patient usually presents with abdominal pain within 3-4 weeks of initiation of therapy and it becomes imperative to obtain clinico-radiological correlation in order to prevent further complications associated with pancreatitis. Leakage commonly occurring at anastomotic site, is seen in approximately 4% of patients following urinary diversion, and was seen in 4 of our cases [20]. An evaluation of excretory phase images is essential in patients with increased output from a drainage catheter or urinary drainage from the wound that might need re-exploration Our study concurs with previous studies highlighting the important role of CT in detection of CrC [10]. In addition, it could illustrate the impact and additional role of CT in cancer patients which extends beyond staging and response assessment. It emphasises the role of radiologists in providing paramount information to the treating physician which has crucial effect on the patient management. The novelty of this study lies in categorisation of the various conditions according to the need and type of intervention required in that particular scenario, with appropriate clinico-radiological correlation; which the reporting physician should be cognizant about. However, it is limited by its retrospective study design conducted in a single centre. It is a descriptive study highlighting the findings seen only on one imaging modality. The impact of management taken into consideration was based on overall general approach whereas actual intervention would differ from patient to patient based on the multidisciplinary team meetings.

Conclusion
To conclude, the study highlights the huge burden of CrC in cancer patients and thus, emphasises the role of imaging in patient assessment. CrC needs early detection and treatment and a radiologist must be familiar with the imaging features and implications so as to timely inform and coordinate with the treating physician. The radiologist must have adequate knowledge of complications associated with cancer including post treatment complications, so that subtle complications are not missed and promptly communicated to the disease management group which can have a grave impact on the further treatment regime of the patient.

Funding
None.

Ethical approval
Institute ethics committee approval for this study was obtained vide letter number IEC-1194/04.12.2020, RP-01/2021.