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Table 3 Studies comparing cancer outcomes within and outside clinical trials

From: Are cancer patients better off if they participate in clinical trials? A mixed methods study

Reference

Population

Type

Dates

En-rolleda

Eligible controls

Treatment similarityb

Potential confounders and methods of control in adjusted analysis:c

Trial effect observed:1

Accounted for:

Unaccounted for:

Unadjusted:

Adjusted:d

1. Arrieta et al. [28]

Advanced non-small lung cancer

RC

2007–2014

143/889

No

No

NBD: Age, wood smoke exposure, exposure to asbestos, tobacco pack-years, brain metastases, ECOG PS, tobacco smoking group

MVA: Disease stage, histology, sex, KRAS mutational status, EGFR mutational status, comorbiditye

RoC: Measurable disease, age

> 18 years, ECOG PS ≤2

SgPA: Received chemotherapye, positive EGFR mutatione

NE: SES

NA:

Treatment centre

Yes

Yes

2. Bertelli et al. [29]

Epithelial ovarian, fallopian tube, primary peritoneal cancer stage IV or sub-optimally

debulked stage III

RC

2006–2010 (trial)

2012–2015 (real-world)

60/248

No

Yes

RoC: Patients managed by the South Wales Gynaecological Cancer Multidisciplinary Team, received at least one dose of bevacizumab as part of first-line treatment

NA: Sex

NE: Stage,

comorbidity, age, WHO PS, chemotherapy regimen

No

Not done

3. De Placido et al. [30]

HER2- positive metastatic breast cancer

RC

2008–2011 (trial)

2012–2015 (real-world)

155/402

No

Yes

NBD: Age, prior neoadjuvant therapy type

RoC: Inclusion criteria: Received tratuzumab and pertu-zumab with taxane as first-line treatment for metastatic disease, no earlier RCT participation in a neo/adjuvant or metastatic setting

SgPA: HR status, previously treated vs untreated with adjuvant and neoadjuvant tratuzumab, visceral vs non-visceral disease,  > 2 metastatic sites vs 2–5 metastatic sites vs > 5 metastatic sites

NE: Comorbidity, PS, SES, treatment

centre, sex

BD: Brain metastasis, FISH / SISH / CISH statu

No

No

4. Field et al. [31]

Gliobla-stoma

RC

1998–2011

61/481

No

No

MVA: Age, IRSAD/SES, ECOG PS, operation type/biopsy

RoC: Two co-located hospitals

NE: First-line clinical trial, comorbidity, tumour location, sex, multifocal disease, operation type, extent of resection, no. of operations, country of birth interpreter, residence, treatment centre, diabetes, smoking, tumour diameter

NA: Stage

Yes

Yes

5. Goldman et al. [32]

Advanced stage melanoma unresecta-ble stage III or IV

PC

2006–2014

115/203

No

Yes

MVA: Sex, primary thickness, primary ulceration, ECOG PS, LDH (stage IV diagnosis), organs with metastases (treatment initiation), metastatic involvement

RoC: Exclusion criteria: Treatments not administered by NYU oncologists, if records omitted pertinent data, patient lost to follow up, therapy administered adjuvantly

StrA: Immunotherapy, targeted therapy

NA: Stage, treatment

centre

SE: SES, comorbidity

BD: Age, prior systemic treatment

Yes

Yes

6. Khera et al. [33]

Acute leukaemia, myelo-dysplasia (MDS), chronic myeloid or myelo-monocytic leukaemia or myelo-fibrosis

RC

2004–2010

494/1353

Yes

Yes

MVA: Treatment, patient age at transplantation, diagnosis, disease risk, graft source, interval between diagnosis and HCT, KPS, HLA match, donor-recipient sex match, GVHD prophylaxis and use of ATG/alemtuzumab, regimen intensity, ethnicity, treatment centree

RoC: Inclusion criteria: Age < 66 years, HCT. Exclusion criteria: Presence of donor-specific anti-HLA antibodies prior allogeneic or autologous transplantation < 12 months prior, HIV infection, pregnancy or breast-feeding, cardiac insufficiency or coronary artery disease requiring treatment, active infection, concomitant enrolment in a phase 1 study, a serum level of creatinine, bilirubin, ALT or AST that was greater than two times the upper limit of the normal range, forced vital capacity, forced expiratory volume in 1 s and/or diffusing capacity of the lung for carbon monoxide less than 50% of the predicted value

StrA: Race, secondary leukaemia/MDS with prior auto, comorbidity, peripheral blood, bone marrow, sex (NBD)

BD: CMV match, donor age, year of transplantation

NE: SES

No

No

7. Le Du et al. [34]

Metastatic breast cancer

(MBC)

RC

2000–2010

285/367

Yes

No

NBD: PR status, radiation, age

previous chemotherapy regimen

MVA: Race, HER2 status, hormone receptor status, number of metastatic organs, previous neoadjuvant vs adjuvant chemotherapy, nuclear grade

RoC: Sex, brain metastases, specific comorbidity, SES/treatment centre; patients living in Harris Country (MD Anderson location), eligible for a clinical trial according to usual inclusion and exclusion criteria for MBC trials and could benefit from the MD Anderson financial assistance programme support

SgPA: ER positive, HER2 positive, triple negative breast cancer

NE: PS

BD: Meta-static sites

No

No

8. Svensson et al. [35]

Metastatic castration-resistant prostate cancer (mCRPC)

RC

2008–2010 (trial)

2011–2016

(real-world)

119/1195

No

Yes

NBD: PSA, time since diagnosis at treatment start, Gleason score

RoC: Inclusion criteria: male diagnosed with mCRPC, aged ≥18 years at time of treatment, treated for mCRPC with abiraterone

NE: PS, SES comorbidity, treatment centre

BD: Age

NA: Sex

No

Not done

9. Temple-ton et al. [36]

Metastatic castration-resistant prostate cancer

RC

2001–2012

43/314

No

Yes

NBD: Comorbidities, Gleason score, extent of disease: bones and visceral metastases, BMI, PSA-dt

MVA: ECOG PS, year of first administration, haemoglobin, log LDH, log time from initial diagnosis, log PSA μg/l, baseline albumin, log ALP

RoC: Exclusion criteria: Patients receiving weekly docetaxel, docetaxel in the context of neoadjuvant or adjuvant trials or as second-line chemotherapy

NE: SES

NA: Sex, treatment centre

BD: Age, extent of disease (lymph nodes)

Mixed2

No

  1. ALP Alkaline phosphatases, ALT Alanine aminotransferases, AST Aspartate aminotransferases, ATG Antithymocyte globulin, BD Baseline Difference recorded, BMI Body mass index, CISH Chromogenic in situ hybridization, CMV Cytomegalovirus, ECOG Eastern Cooperative Oncology Group, EGFR Epidermal growth factor receptor, ER Oestrogen receptor, FISH Fluorescence in situ hybridization, GVDH Chronic graft-versus-host disease, HCT Hematopoietic cell transplantation, HER2 Human epidermal growth factor receptor, HIV Human immunodeficiency virus, HLA Human leukocyte antigens, HR Hormone receptor, IRSAD Index of Relative Socioeconomic Advantage and Disadvantage, KPS Karnofsky performance score, LHD Lactate dehydrogenases, MVA MultiVariate/MultiVariable/MulticoVariate Analysis, NA Not Applicable, NBD No Baseline Difference, NE Not Evaluated, NYU New York University, PC Prospective Cohort, PS Performance status, PR Progesterone receptor, PSA Prostate specific antigen, PSA-dt Prostate specific antigen - doubling time, RC Retrospective Cohort, RCT Randomised controlled trial, RoC Restriction of cohort, SES Socioeconomic Status, SISH Silver in situ hybridization, SgpA Subgroup Analysis, StrA Stratified Analysis, WHO World Health Organisation
  2. a Values are number of participants in trial/non-trial group
  3. b Similarity between the treatment received by the trial participants and the treatment offered in the control group (for randomised controlled trials) and that was received by non-trial participants
  4. c We assessed whether each study attempted to account for possible confounding by age, sex (where applicable). PS, comorbidity, SES, stage (where applicable) and treatment centre
  5. d Adjusting for confounders by using multivariate or multivariable models, stratification, subgroup analysis, restriction of cohort
  6. e The methods section describes that this was adjusted in multivariate analysis but the results are not presented in the result section
  7. 1p < 0·05, unless otherwise noted
  8. 2 The Kaplan-Meier analyse showed a trial effect (p = 0.007), but the univariate Cox proportional hazard ratio did not (p = 0.089)